Under weight. The diet what he said.

Dear sir /mam I am a female 24 years old height 159cms weight 45kg my problem is under weight, due to motions daily 2 or 3 times loose or normally with stomach pain before going stools. I have been consulted a doctor(senior physician) 3 months ago. i told my problem. he wrote some medical tests CT scan and stool test, no infection or problem in reports, he wrote some medicines and he said some diet to control stools. what he said i given below : 1)don't eat non-veg 2)don't take milk products 3)wheat also don't take if it not suits you 4)don't eat spicy foods iam following the diet what he said. after one month i have consulted again he said try some foods which suits you, now iam eating egg,fish, chicken and not all dairy products iam having curd only and daily I will drink cooked rice water. Iam following proper diet what he said, but it still continues, iam having stools daily 3 times iam not yet increasing weight still. tell me what I have to do, how I will increase weight