Hello. My 22 month old has some sort of diaper type rash on her bottom. It s not really a rash but more like giant pimples . She only gets one at a time but they are huge and very painful. She walks funny when she gets on and does not like being carried when she has one. We had to pop one the other day and we squeezed a lot of pus out. The pus was about the size of a quarter. She has another one now and it has made her one bum cheek look larger than the other. It has not formed a head yet so I can t pop it. Any idea what this is?