Man I know what it's like watching your dog go through rough stuff and not to be able to do anything to help him...
My big sister had a dog that she got when I was about 8 so I grew up with him and when she still lived with me and my mom I took care of that dog when she went to work or whatever and I loved him like a brother.
When he was about 9 he started getting seizures and the vet didn't really know whats wrong with him, after a while he was having a seizure every 30 minutes and he would pee on himself so my sister had to put him down.
I wish your dog well, keep us updated on his situation.