Michelle,
I am so glad the transfer factor is making a difference. I'm not sure what all you've tried so far. It seems to me that if it were a reaction to the flea med. there would have been some sort of antecdote. I had something similar once happen with an ear mite treatment. Also, it seems it would be good to flush out his system as much as possible. Did the vet give him fluids? Anything like that?
tonya
