Is this his first grooming? A new groomer, perhaps? I have 2 dogs that act weird (For 3 days) after a grooming. The rear end pain is probably for the Anal Sac expression. It drives mine crazy, but they seem to get over it on day 3. The wobbling legs concerns me, though. Look for a razor burn or cut on the bottom of his feet. Apply an antibiotic ointment where you see any unusual red areas. I still would get him checked out by a vet. Then you'll know what to expect the next time. Hope he is better today...Karla
If he were my dog, I'd be making an appointment with my vet. There is no telling if something happened with the groomer, but something is definitely not right. I know it's a holiday today, so if you can't get him in to your regular vet tomorrow morning at least find an ER vet to check him out. Hope it's nothing serious. :-)