Sebastian
This may not be the case with your dog, but Mine, Chaos was collapsing, an drooling alot. After walking only a few steps he would fall. I took him to the vet umteen times with wrong diagnosis's (i did my reasearch.) The symptoms did not match the diagnosos.
finally after hundreds of dollars and A fantastic Vet in sunvalley Idaho, he was properly diagnosed with
Acquired Myasthenia gravis, it goes hand in hand with megaesophagus (which will cause the drinking and drooling) It is rare, but worth checking into if all else has failed.
His vet (MR. Misdiagnosis) told me to put him to sleep!! NO WAY!! I will never take him there again, from now on we make the trip to Sun Valley. Chaos is fine now with his medication. I tried to e-mail you with this info an couldn't but I emailed the administrator. I'll be praying for you and Sebastian because I know how scary it can be to not know what is going on!!
anbuh