Hi.. Thanks for the query.. If you have an abscess under a tooth then it will commonly cause a white pimple like lump on the gum.. Swelling on cheek is probably due to abscess. But the purple lump if it is under tongue then it can be probably a Mucocele or mucous cyst.. Taking antibiotics will reduce infection and abscess but it will not resolve it completely.. For complete resolution consult a Dentist and get evaluated.. An x ray should be done.. If tooth can be saved Root Canal treatment should be initiated followed by antibiotics and painkillers.. If there is gross decay extraction is advisable.. Hope this helps.. Regards..