My Name Is Michelle, I Have Boils Again, Very Painful.

My name is Michelle, I have boils again, very painful. I have an old prescription of sulfa, how long after expiration can I use them? I moved here awhile ago and cant afford health coverage. I also have allergic contact dermatitis and my skin is to the point it drains puss & then the skin falls off in layers. Can you please help? Desperate Grandma seeking any relief.