For my -6 year old son who has severe acne on his face for about a year. We used all prescribed and OTC creams, etc and nothing works.
We have been 2 different dermatologists and they want to put him on Accutane. We decided against it as we know a number of people whose children were on it and it caused severe side effects. The 2nd dermatologist didn’t even thoroughly look at my sons face but as soon as he walked in the exam room door said you need Accutane.
I don't blame you. My teen has had severe acne and I've also read all of the terrible side effects that can come with Accutane use, which is why we've avoiding putting her on it. Some people do fine with it, while others end up with life-long problems. There's no way to know which category your child will end up in, so I was not willing to take the risk.
I can tell you that I personally know four people who've taken Accutane. Three of them did fine, ended up with clear skin, and said they'd absolutely do it again. Only one of those three was left with lasting and painful dryness in his nose. The fourth person I know took Accutane in her teen years and was fine for a while. Then in adulthood, she developed a severe and rare digestive condition that required emergency surgery and the use of proton pump inhibitors for the rest of her life. I can't definitively say that the Accutane caused her problem, but I do suspect that it may have been a factor.
But because 6 years old is so young to be dealing with severe acne, if this were my child I think I might try taking him to an endocrinologist to get checked. OR you could try adjusting his diet to see if that has any impact on his skin. We recently discovered that dairy--especially fat free or skim milk (due to the hormones in it)--was contributing to my daughter's severe acne. While researching options for her, I stumbled across a YouTube site that suggested dairy as a causative factor in severe acne. The possibility had never crossed my mind before, so we tested it out and my daughter's skin did show an improvement after just a few days. Several weeks later, she gradually began to slowly re-add some foods back into her diet (like cheese) to see how it affects her skin. So far, she's still be doing well, which is why I believe the fat free/skim milk that our family has used since she was a baby was most likely the biggest culprit for her. She is able to drink whole milk now with no problems.
Anyway, I really wish I had better advice for you. I am so sorry your baby is suffering with this, but hopefully something I shared can help you find the solution.