Stomach Bloating, Diahoria. Suggest.

My 3 years old son suffering loose motions from last 3 days, Day 1- vomit 3 times, water stools 9 times Day 2- no vomit, water stools 7 times Day 3- vomit 1, stools become less watery 3 times Upper stomach fullfill most of the times and before pooping is also feel lillte pain. Take Tufpro twice, Bestzyme sy twice & cyclopam syrup twice a day, ORS but no cure still, Now stools are less watery than previous but not normal, also every time he feels gassy, not to eat properly due to gas and one cankar sore on mouth. Me also suffered same for last couple of days ago, my doctor give me antibiotics for that. But my pediatrician not my son to give any tipes of such antibiotics.. or any gas medicine to prescribed. Please suggest.