My dog is 15 yrs old and has had loose bowel movements for the last 4 days. I have tried to give rice, immodium and other stuff. Nothing works What can I do?

My dog is 15 yrs old and has had loose bowel movements for the last 4 days. I have tried to give rice, immodium and other stuff. Nothing works What can I do?
I think I would call the vet at this point. Four days is a long time and the dog will become dehydrated. Good luck.