It is poison ivy and it looks like he is already scratching and spreading it. Get a poison ivy scrub to get rid of the irritant and then get a calamine mix that has a topical anesthetic in it to relieve the itching so it can heal.
I understand your suspicions of your ex, the difficulty with a child who cannot express himself but common sense dictates that a very unusual (if you aren’t familiar with poison ivy) thing like these blistered spots you reserve judgment and take the child to a doctor even if it’s expensive and also perhaps heed the remarks of several people on this thread who said poison ivy rather than dismissing them out of hand. You really did make yourself look foolish by jumping to rather drastic assumptions about your ex. Accusations like that are very damaging and should be made not first, but last after other explanations have been exhausted.
I appreciate your input. Respectfully, I’d like you to reread what I wrote. I never said she did something nefarious or even implied it. If anything, I implied a lack of responsibility. My entire post, at 2am, was not to bash her, but to get some opinions in the absence of an explanation from here. Poison Ivy wasn’t dismissed out of hand, but the opinions of Born to Conseve was because he came into this thread - which was simply me asking for opinions on something - and decided to make it a personal attack against me. For no reason. I don’t know if he was in a sour mood given the news he’s read or what, but he pushed my button (which may have been his fun for the evening, I don’t know) and I pushed back.
I appreciate everyone’s sage advice. In the absence of her intentionally allowing my son to be harmed, I would never take a mother away from a son. I have a decent relationship with my ex, with the exception of her putting herself before the kids at various times over the last couple of years. For me, my kids come first - and that means their safety and their need to kick the tires, so to speak, and get into a little trouble. But like many of you have stated, when you have a child that cannot communicate their feelings or simply “have you been scratching?”, then you have to investigate everything and you have to KNOW the cause or you wonder if it was something you did or could do again to him.
Since I am not a doctor and since it was late evening when I noticed it, i went through WebMD and google images, didn’t see a match, so I posted here hoping for some info. I’ve had poison ivy and it’s never looked like that. We’re taking him in this afternoon to be sure. I will let everyone know what they diagnose. Thanks for all the well wishes. Off to work I go. Thanks again.