I'll check out those links-

The rash is pretty much all over, pinkish and slightly raised patches, then little blisters will appear and burst, and if he does scratch it gets raw looking.

Dietary info-
He seems to think meats or meat juices give him stomach problems. {IBS}
he can eat jerky and turkey dark meat with no troubles.

At one time last year we did wonder if Celiac was a problem but I sent him the links to read about it and he said he thought not.

starches seem to not be an issue.

but I'll reread again in case we missed something.

here's a photo similar to his rash-