Severe rash in my armpit, can you help me? About a month ago now, I got a large hard lump in my armpit. I left it alone, hoping it would go away. It got bigger and redder and started to hurt. About two weeks ago it ruptured. It had lots of pus and clear,

Need eval. Regardless of what the inital rash was, it sounds like you either had a cyst or an abscess that ruptured. Please have his evaluated.
It . It sounds as though you may have a skin infection with abscesses or "boils". These usually start out as tender, red areas which become hard and then eventually develop a "head" of white pus. Once this drains, the area usually heals on its own. Most of these are caused by staphylococcus aureas, a common bacteria found on the skin. Occasionally, however, the can be caused by mrsa, the antibiotic resistent kind of staph bacteria. If the infection is not getting better after drainage, then you may need antibiotics and should call your regular doctor. Next time you develop one of these infections, start out by applying warm compresses to the area to help draw the infection out. Then, you should go to the doctor so that they can drain it, test for what bacteria is causing it and be able to treat you appropriately - sometimes with antibiotics, sometimes just with drainage. If you ever develop fever, chills, or feel ill with this infection, call your doctor immediately. You can try and prevent these infections by practicing good hygiene and using anti-bacterial soaps. Your doctor may have other suggestions for prevention.