Problems with my 10 year old schnauzer, help

Hi so we have a miniature schnauzer that’s is a ten year old male, now the last month he has been behaving very weird and tail will go down and he’s frozen in place with his paw up, I know he’s trying to tell us something but I don’t know what it is, we thought maybe it’s a stroke but blood tests came back normal at the vet and they figured it was pain and gave meds. Now he’s still acting this way and it’s not pain I don’t think, please help this is my grandfathers dog and idk how his 75 year old heart will handle it if something were to happen. Thank you