Diarrhoea and weight gain issue. Issue?

My daughter is 8.5 months old. Past three weeks she was having soft stool 4 times a day. Past few days, it turn into watery stool 8 times. This month she fail to gain weight which is 6.5 kg last month and 6.6 this month. She is irritated now. She is not having fever. Teeth has not come out. She is on breast milk, overcookedrice dal, coconut water, order/glucose and homemade carelac. We stop giving her fruit as of now. She also vomit occasionally. We had her checked and is on walamycin and darolac. Her symptom got improved after medication but today she started having watery stool again. We had her stool test done.  Her stool ph is 6 and tested negative for reducing substances. What should be done to cure her issue? Please suggest we are little worried