Hi.. Can understand your concern.. As per your complain the stomach upset occurs as a side effect to some people due to antibiotics and Clindamycin is antibiotic used to treat a variety of infections including dental infections. This happens due to disturbance in the normal bacterial flora present in the intestine and disturbs the delicate and complex functioning leading to stomach upset. For acidity and heart burn: I would suggest you to take Pantoprazole 40mg every morning on an empty stomach. If you have acidity or discomfort after eating you can take an antacid liquid like digene or gelusil half an hour before meals. In case of loose motions: Lomofen which is an effective anti-diarrhoea medicine can be taken as it helps in relieving diarrhoea. Avoid processed food.. Avoid very spicy and high fibre food as the high fibre food takes more time to digest.. Take more of liquids to avoid dehydration as there is more of water loss in diarrhoea. In case you are constipated then Bisacodyl (Correctol, Dulcolax) can be taken as it is a laxative and helps in lubricating the stool as well as relieving the constipation. Taking high fibre foods containing green vegetables, wheat bread etc can help.. In all conditions keep yourself well hydrated.. Hope your query is solved.. If you find the answer helpful please write a positive review and click on find this answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora.