I know I do usually phone the vet pretty quickly when I have a problem but he was so non-specific: just failing to thrive really, no actual symptoms to talk about, he just kept slipping downhill for no obvious reason. Plus I wasn't really looking for watery mouth and am now kicking myself that I didn't think of that as a possibility earlier. The trouble is I've been trying to boost him up and I think you get so fixated on that course of action and looking for signs of a turnaround you don't really see that you're just prolonging the agony.
Sometimes you just need someone to tell you to get on with it - I'm on my own here and don't really have anyone to use as a sounding board or give me a kick up the backside when I'm failing to see the obvious, which is why this forum is so invaluable... x