Hello D.,
I feel for you. I'm in a bit of a hurry so I'll be direct and to the point of sounding blunt/judgmental....
please know that I'm NOT judging you in any shape, way or form.
I'm surprised your doctor had you try a different milk after only 3 monhts! you usually should wait more like 12 months. your baby definitely needs to be seen by an allergist. check www.enterolabs.com for stool sample tests, etc. there are tests that can do while waiting for your baby to be older in order to do the skin test.
when confronted with allergies...it's a big learning curve. it will be overwhelming for a little while, then you'll be OK. Get ready to read every food label, every time... even lotions, shampoo, medicines, laundry degergent, dishwasher detergent, etc.
Read all you can about allergies. learn the many names of WHEAT. read about celiac's disease. it might not be what your son has, but it sure helps you learn how to spot wheat...which unfortunately is in almost everything! (the same for soy and corn!)
http://www.celiac.com/
http://www.livingwithout.com/?p=all_glcd&s=gl_pd&...
http://www.livingwithout.com/2009/augsep09-backtoschool.html
http://allergykids.com/
http://foodallergy.org/
With so many allergies, you'll be better off making everything yourself. it's the only way you can really make sure what he's getting. and you'll have to train everyone not to give him anything without checking with you FIRST. As your baby gets older, read about cross-contamination (depending on the severity of the allergy).
I know neocate is soooo expensive.
remember, read food labels EVERY TIME because they DO change/substiture ingredients.
feel free to challenge the doctors opinions. you know your baby. sometimes they'll recommend stuff that you know it's wrong for your baby. ask for alternatives. You are your child's advocate.
keep a food journal and the status of his bowel movments (date, time, consistency, smell, color, etc.) take pictures if needed so you can compare. it might sound gross but it's your son's health.
Good luck and keep asking questions until you get the right answer for you and your baby!
~Carmen~