hi my fried had a problem with his salvia ducks,he went to his doctor who gave him antibiotics theyndidnt help ,he has got a small lump under his tonuge and cannot open his mouth wide only slightly, he is getting terrible headaches and toothache he is terrifide of dentists ,his doctor wouldnt give him anotherstronger antibiotic, he thinks it might be an abcess could you enlighten me to what the cause may be