It may be caused by something he is eating. Like eggs or dairy products. When my son was 10 months he had a reaction to cheese. He outgrew it though. And now at 18 months he is fine
If you haven't tried a perfume and dye free detergent, that may help tremendously. ALL free and Clear is your best bet.
Have you maybe considered that its the dreft thats causing it? My firstborn was VERY allergic to dreft. We found out it was the perfume in it that was irritating her skin. Yes Aquaphor is sold at walmart, they have Aquaphor baby and reguler aquaphor. There the same in my opinion.
We switched EVERYTHING literally , we even wash our stuff in dreft. He's been on the hydrocortisone cream , lotion && ointment but nothing works && is Aquaphor sold at Walmart ?
Aquaphor baby is also great to use for it.
I used the aveeno excema therapy lotion. Also, have you tried switching laundry detergent?