Strange bumps on my baby

This morning my 10 month old baby woke up with what I thought were mosquito bites all on his torso. I didn’t think much of it and went about my day. When I was putting him to bed I noticed the bumps had multiplied. So it’s obviously not mosquito bites. So I’m thinking maybe chicken pox or hives? I’m planning on calling the doctor in the morning. Any ideas on what it might be?

Update: the doctor says it’s erythema multiforme minor. It’s gotten worse on some areas of his body since I took that picture but a bit better in others. The doctor recommended a tiny dose of Benadryl every 6 hours (literally less than 1/4th of the amount suggested on the box for children) I don’t know if it’s working. He said it was a cousin to hives and caused by something his body overreacted to. I don’t know what he’s reacting to. Apparently it usually lasts 2-4 weeks but may come back again. I’ve had skin issues myself before and I had hoped my child hadn’t inherited my sensitive skin. 🙁