My 6 year old Dachshund has been having loose stools lately and doing them in the house, which is highly abnormal for him. He's in very good health, has his teeth cleaned regularly, all his shots are up to date and he's very active, despite his stool issue. Can I give him over the counter medication, such as Pepto-Bismol to help with the stool issue, or would you recommend another? Note: I have another Dachshund (1.5 years) that isn't affected by this stool problem. Also, this event started a week after we (dogs included) returned from a trip from Mexico. He drank bottled water while we were there. Any comments would be greatly appreciated.