What Do Inflamed Bumps On The Buttocks Along With Fever Indicate?

I hv a recurring warm bumps on my butt for a month nw accompanied with fever. New bump appears when old is cleared. The bump is not visible outside but is sensed when touched. The bump is also hard. It appeared on the same track vertically on my left bum. I am confused this with liposarcoma as it is occurring recurrently. I hv recently delivered & I was diabetic during pregnancy. I also have fungal infection since pregnancy 6 months till nw & it got cleared somewhat excpt on the bum where tumor is appearing. This is stressing me a lot.. Pls suggest if this is serious or it has to be surgically removed or medicines fine