V.L.
Does this happen after bath time? or is it something he eats? see if you can pin point what triggers it. Dr's dont always know what it is. You can read about my personal experience with Dr's and rashes on my blog at http://valerielint.blogspot.com/
To much info to write in here. If you find its an allergy to what you are using in the home contact me and i will be more than happy to help you. Or if you just want to become a Chemical Free home