Hi.. Thanks for the query.. Yes, you can take Amoxicillin with flagyl and to avoid any gastric complications you can take empty stomach Omeprazole and plenty of probiotics like Yogurt.. Now an additional information is that if there is so much of pain that is radiating to jaw as well as ear then there is a possibility that the filling is accidentally placed directly over the nerve that is present deep in the tooth. The nerve might be getting irritated leading to pain.. Get an x Ray of tooth done to confirm the cause If the filling is over the nerve then removing the filling under local anaesthesia should be done followed by Root canal treatment of tooth.. As of now along with antibiotics take anti inflammatory painkillers like Ibuprofen and also do cool compresses over the cheek.. Send me your x Ray so that I can advise you the most appropriate treatment for you.. Hope you get better soon.. Regards..