I can appreciate your concern regarding these two symptoms. The urgency to have a bowel movement and loose consistency of the stool must be very disturbing. Have you spoken with your gastroenterologist about these symptoms?
I am not making a diagnosis, but you could possibly be experiencing postcholecystectomy syndrome (PCS). PCS is caused by alterations in bile flow due to the loss of the reservoir function of the gallbladder. Two types of problems may arise. The first problem is continuously increased bile flow into the upper GI tract, which may contribute to esophagitis and gastritis. This may be what is causing heartburn after eating or drinking.
The second consequence is related to the lower GI tract, where diarrhea and colicky lower abdominal pain may result.This may explain your urgency to have a bowel movement and the loose consistency of your stools.
According to Michael F. Picco, M.D. a Gastroenterologist with the Mayo Clinic, "It's not clear how many people develop the frequent loose, watery stools that characterize diarrhea after surgery to remove their gallbladders (cholecystectomy). Studies have found as few as 1 in 100 people undergoing gallbladder surgery or as many as 1 in 3 develops diarrhea. In most cases, the diarrhea resolves soon after the surgery. Rarely, it may last for years. The cause of diarrhea after gallbladder removal isn't clear. Some experts believe that it results from an increase in bile, especially bile acids, entering the large intestine — which may act as a laxative."
I hope this information has been helpful to you.