Ok, I have a couple questions to ask anyone who can answer.....

1. Why exactly do they give you shots in the hip/buttocks? Is there less chance of infection there? Because I've noticed they never bandage it or anything. And they hurt.....

2. OK, here's the thing.....I've become extremely frightened of getting the "flesh-eating bacteria" (Necrotizing Fasciitis).....Here's why.

A few days ago I got a small cut on my left outer thumb. No big deal, right? I washed it, but in my stupidity didn't put a bandage on it. It got a bit pink around the edges for awhile, but noting too bad. Then yesterday all of a sudden my thumb begins to hurt really badly.....Burning, for no reason. That goes away pretty quickly, but is replaced with general pain when I put pressure on it. And keep in mind this is on the INSIDE of the thumb now, completely opposite of where the cut is. It's become pretty red. I went to the ER and got Keflex (Antibiotic) and a shot for my headache (Toradol). Now here's where my question about shots comes in.....I'm now really afraid that the place where I got the shot in my left buttock will get infected.....How fast do they heal? Are they even at much risk for infection? I know I'm really just worrying a whole lot, but could someone maybe calm my fears a bit, please?

There are three primary types of injections: subcutaneous injections, intramuscular injections and intravenous infusions.

The on in the buttocks is called the intramuscular. Each type of injection has a different purpose or medication acts differently with each type. When it comes to an intramuscular they can put it in the deltiod muscle or the buttocks, most doctors will choose the buttocks not because of an infection risk but because it is in fact the biggest muscle in your body outside of the heart. Therefor when doing these types of injections the buttocks is actually the most effective overall.
It will take several days for the pain to go away and sometimes you will feel a hard knot but it is nothing to be concerned about unless it is very red and possibly looks infected. The risk for infection from any injection is incredibly low.
Honestly I would not worry about it.

Your thumb probably got a mild infection in it and the Keflex should take care of it. If it continues to be painful I would suggest you go and get it checked again, even if it is only for peace of mind since you seem so worried.

As for the flesh eating bacteria here is some basic information:
What is necrotizing fasciitis?

Necrotizing fasciitis is a rare bacterial infection that can destroy skin and the soft tissues beneath it, including fat and the tissue covering the muscles (fascia). Because these tissues often die rapidly, a person with necrotizing fasciitis is sometimes said to be infected with "flesh-eating" bacteria.

Necrotizing fasciitis is very rare but serious. Around 30% of those who develop necrotizing fasciitis die from the disease.1

Many people who get necrotizing fasciitis are in good health prior to the infection.2 Those at increased risk of developing the infection are people who:

Have a weakened immune system or lack the proper antibodies to fight off the infection.
Have chronic health problems such as diabetes, cancer, or liver or kidney disease.
Have cuts or surgical wounds.
Recently had chickenpox or other viral infections that cause a rash.
Use steroid medications, which can lower the body's resistance to infection.
What causes necrotizing fasciitis?

Necrotizing fasciitis is caused by several kinds of bacteria. The most common cause is infection by the group A streptococcal (GAS) bacterium, which also causes other common infections such as strep throat or impetigo. Usually the infections caused by these bacteria are mild. In rare cases, however, the bacteria produce poisons (toxins) that can damage the soft tissue below the skin and cause a more dangerous infection that spreads through the blood to the lungs and other organs. The disease also may be caused by Vibrio vulnificus. Infection with this bacterium can occur if wounds are exposed to ocean water or the drippings from raw saltwater fish.

Another type of necrotizing fasciitis may be caused by bacteria found in the intestine; this type most often affects people with diabetes or peripheral arterial disease. Occasionally people who have gunshot injuries or tumors in the lower digestive tract develop necrotizing fasciitis.

A break in the skin allows bacteria to infect the soft tissue. In some cases, infection can also occur at the site of a muscle strain or bruise, even if there is no break in the skin. It may not be obvious where the infection started because the bacteria may travel through the bloodstream to other parts of the body.

The bacteria that produce the toxins that cause necrotizing fasciitis can be passed from person to person. However, a person who acquires the bacteria is unlikely to develop a severe infection unless he or she has an open wound, chickenpox, or an impaired immune system.

What are the symptoms of necrotizing fasciitis?

A person may have pain from an injury that lessens over 24 to 36 hours and then suddenly becomes much worse. Other symptoms may include fever, chills, and nausea and vomiting or diarrhea. The skin commonly becomes red, swollen, and hot to the touch. If the infection is deep in the tissue, these signs of inflammation may not develop right away. The symptoms often develop suddenly (over a few hours or a day), and the infection may spread rapidly and can quickly become life-threatening. Serious illness and shock can develop in addition to tissue damage. Necrotizing fasciitis can lead to organ failure and, sometimes, death.