Dog continuously kicking and twitching hind leg and tail

My 13 year old Japanese spitz dog started having strange episodes since 16 hours ago. He is currently taking pantoprazole and Doxycycline for a suspected Ehrlichiosis infection since 3 weeks. Blood test 1 week ago showed platelets and liver enzymes improvement.

His left hind-leg keeps kicking randomly and tail vibrates at the same time. The leg kicking is similar to what they do if we tickle their paw furs.

Every thing else is normal. He walks normal and he is drinking water, going to the bathroom and eating normally but he is unable to rest. This has kept him up all night and he gets agitated when it happens too strongly. He is able to fall asleep for a few minutes at a time but his leg keeps twitching slightly and then he gets woken by spontaneous leg kicking.

The only thing that stops the kicking is when I massage his thighs and on the back near the base of his tail, and starts up immediately when I stop.

This seems like a nerve related issue as I have checked his foot and it doesn’t hurt him. We are waiting for the vet to be available but I was wondering could this be an emergency issue? Could this be a reaction to his medication? And what solutions might the vet offer? we are very worried so some opinions would be appreciated.