Recommend Diet To Be Taken While Suffering From Diarrhea

We returned from a holiday in India last Thursday and my husband, who is 73, has been having severe diarrhoea since last Tuesday. He was given 6 tablets by the holiday rep. who said they treated the local form of bacteria-the tablets had Ofloxacin and Ornidazole - Oflotas-OZ written on the back of the pack. He only took 3 hoping that this would enable him to travel home without incident, which they did. He now has stomach cramps, slight shivering episodes and continues to have watery motions 4 days after arriving home. We visited a locum doctor yesterday who told him to take Immodium 3 times a day and 2 Buscopan 3 times a day for his stomach cramps. He was also told to eat plain rice, mashed potatoes and tea biscuits and ensure he had plenty of liquids. He continues to have watery motions but is saying he is hungry (the first time he has felt hungry in several days). What would you advise for me to give him to eat?