Well, Bogart threw up again last night.  He ate (still blenderized I/D) around 6:30 and then he threw up around 9:15.  He was behind my husband when he did it so we aren't sure if he actually "threw up" or just "regurgitated" it.  This time, unlike the other times, it was very watery, although you could still see his food in it.  This is just so darn perplexing because he is now getting sick about every other day, once a day????  And we still can't find any pattern to this.  
 
Amandawash - I do not think that he has been diagnosed with allergies.  I will call my vet right now and ask about allergy testing - I don't know why it hasn't been done yet???  The change in food is largely my husband and I's idea ... we are just desperate.  The internalist suggested that we just try something non-poultry related and then the other vets made suggestions about what we should try, although none of them seem to think it is food related.  But - they can't tell us what it is either!!!!  It is just getting so frustrating, not for us or our pocketbook, but I just want to do whatever it takes to help Bogart feel better - and I feel like such a bad mommy that I can't help him stop throwing up 
 
  
Thank you all again for your help and suggestions.  I am determined to figure this out and help Bogart - I will do anything!