I've heard that Dr. Shampain is awesome! We actually have an appt for my son to see him too. HOWEVER, he has a waiting list about 3 miles long! I called a month ago & wasn't able to get in until November. There was a cancellation while I was talking to her, so I got in in August, but still! That's a LONG time!!!!!!!!!!!!
In the mean time---if you're formula feeding, it's likely the formula that's causing it. Many babies are very sensative to the milk proteins or soy proteins. If you're nursing though, then you can simply cut out some things from your diet that are more likely to be causing the issue. I'd start with all dairy and see what happens. If that doesn't help, cut out soy or wheat.
You may also want to try some organic/all-natural bath products (shampoo, lotion, etc...). The "mainstream" stuff is LOADES w/ harsh chemicals, some of which have a track record for being very dangerous.
I hope that your poor son gets some relief!