My DD had horrible diaper rash; sometimes I thought the skin would start to bleed it was so bad. We found out later she had and still has quite a few food allergies - eggs, orange(citrus including strawberries), pork, and milk to name a few. Why don't you see if you all can keep track of what GS eats and any reaction to those foods? All the suggestions here sound good to me. Most any one would help. Good luck.