Raised Dime To Nickel Sized Areas On The Skin Of

raised dime to nickel sized areas on the skin of the knees, elbows, shoulders and hips. Areas on hips are larger. raised areas with pustules, also occurring inside of mouth and throat causing pain, inability to eat and swallow. Mouth/throat symptoms occurred about 2 months ago, steriods made symptoms subside, but now are reoccurring with the skin areas being affected now as well. What could this be?