answer:[not a vet] I am a life long pet owner, though. First of all, Tylenol is safe, but I prefer aspirin as it doesn’t cause/contribute to liver failure for older dogs. I’d say this sounds like a urinary tract infection or a kidney issue. I’m glad to hear you have a vet appt. scheduled. If you can, collect some of the urine before the visit, do so. If only keeps for an hour refrigerated, so keep that in mind. I’d go with any blood tests your vet recommends, too. My elderly Jack Russel began doing this his last year/year and a half (he passed in autumn at 17) in occasional bouts, then it got more frequent toward the end. He had kidney issues due to his need for steroids for his allergies. We did not medicate him for the condition.