Several Weeks ago I applied Sentry Pro XFC on my dog Jake and by the next day he was chewing himself allot along with acting very nervous. by that night he also started dry heaving. After searching the Internet I saw that this has been a very common and dangerous reaction to the Flea & Tick medication I had applied. Luckily Jake did not suffer the kidney failure or extended stomach from the dry heaving.
The Blog that I have found allot of good advice in dealing with this problem is
I suggest going there but I also Suggest calling your vet also.