I hope this isn't violating any rules, we just have no idea what to do and I figured it wouldn't hurt to ask a dog centric group!

Video first

My dog (Watson) has been having episodes like what is shown in the video a couple of times per day for the last few days, probably approaching a week.

We took him to the vet on Monday but they were unable to locate the source of his pain following two oral exams and visual inspection of the paw that is in play. They suggested we try to film the next time it happens (hence the video)

He looks like he's in a ton of pain, but whenever we try to locate the source he no longer appears to be.

As an aside he is epileptic but has been on drugs for it for several years (and the vet is very aware of all that).

Anyway, if you've ever seen anything like this before we'd very much appreciate any information anyone has.

Thanks in advance!