Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that your girl has been walking restlessly for 4 hours.
I understand that she was examined recently and given a clean bill of health, but at that time she wasn't displaying these symptoms. At 15 &1/2 years of age things can change very quickly for them healthwise.
Was bloodwork checked at that point?
When was her last dose of aspirin?
Aspirin can cause side effects but they are usually gastrointestinal (vomiting, diarrhea, either of which could be bloody, lack of an appetite, or bruising, blood in the urine or bleeding gums). I would not expect aspirin to cause restlessness UNLESS she suffered bleeding in her brain or has a very upset stomach, in which case I would expect her to be vomiting or show signs of extreme abdominal pain.
If you feel her symptoms may be due to an upset stoamch at home you can give either:
- Pepcid ac (famotidine) at a dose of ¼ of a 10mg tablet every 12 hours
- Prilosec (omeprazole) at a dose of ¼ of a 20mg tablet every 24 hours
These are acid reducers and may help her feel better enough to settle. They can be given for several days if necessary.
Otherwise I would be concerned about things that affect brain function in an older dog causing her symptoms.
Those would include metabolic diseases leading to waste products building up and affecting brain chemistry (kidney or liver disease), low or very high blood sugar, a blood clot blocking blood flow in her brain, or even granulomas or masses in the brain.
I highly recommend your girl see her veterinarian promptly.
Please let me know if you have any further questions.