Yeast Diaper Rash turned into a boil?

Patient: My 10 month old son currently has a yeast diaper rash. He has seen a doctor and it is being treated. It is looking much better but today I noticed that he has a bump on his genital area. It looks to me like the beginnings of a boil. I have had experience with boils with my older son and don’t want it to get out of control. I am sending a picture of the boil. Please tell me what you think and what are my treatment options before it gets to big.

Doctor: