Long lasting reaction to Promeris

Hi
I have a Tibetan mastiff. I used Promeris duo at the end of August for the first time because I couldn't get my usual Frontline.I have never read any reports on it until a few days ago and I was amazed to see exactly the same reactions as my dog had - within a couple of hours she was drooling, unsteady, her head and tail hanging and then sleeping so deeply I had difficulty in waking her, and totally unresponsive to voices.
Our vet says that adverse reactions to promeris only last 1-2 days, so she has been seeing a specialist for various tests inluding CT scans, lumbar puncture and analysis of fluid from her joints to find another cause.
I still don't believe that it is a coincidence that in the morning she was a perfectly healthy dog, had her tic treatment lunchtime and then in the afternoon, virtually collapsed;
PLEASE can anyone tell me if they have heard of Promeris reactions that last for more than a few days. It is 6 weeks now and she has only made a slight improvement (since being put on a vaso dilator)
thanks, dogue du thibet