I have recently developed hard red bumps with a pus- filled head on my leg, belly, and arms. I was just taken off metformin because I was allergic to it. My skin rash cleared up with the help of steroids but it is now coming back and I am getting these so

Folliculits. May be related to the steroids, which has affected the normal and healthy bacterial flora on you skin.
Folliculitis. Folliculitis is inflammation of one or more hair follicles. It can occur anywhere on the skin. Folliculitis starts when hair follicles are damaged by friction from clothing, blockage of the follicle, or shaving. In most cases of folliculitis, the damaged follicles are then infected with the bacteria staphylococcus (staph). Antibiotics are the treatment of choice.
Abcess? see doc! This may or may not be related to a metformin skin rash. If there is a break in the skin from the rash it could have allowed bacteria in causing a staph skin infection. It is hard to tell from a question how large the bumps are and if they represent and infection, so i would recommend seeing a doctor to see if antibiotics are needed asap- if it is an infection it can get worse quickly without help.
See your doctor. This problem can only be solved by seeing your doctor and being evaluated face-to-face. After a thorough examination, your doctor should be able to tell you what's wrong and what to do about it.