You can send a link to somewhere you've posted the pictures, but my experience on here is nobody will look at them probably. The steroid probably made it much more likely it would come back, and antibiotics may very well do the same thing, as both types of drugs can adversely affect the immune system overall. But without a diagnosis, you can't really make a decision on how to treat it, and if it's not an allergy, it could be a fungus, it could be bacterial, it could be some type of bug sting or bug bite -- almost sounds like he sat in an ant hill -- so you just have to find a better doctor, I think.
Is there one spot larger than the rest, a “mother spot” so to speak? Google pityriasis rosea
Any chance it could be scabies?