thanks for your query, i have gone through your query. the ulcer on the palate could be reccurent herpes or aphthous ulcer or it can be a fungal infection like mucormycosis or it can be a pus discharging sinus tract. consult your oral physician and get the radiograph done to rule out tooth infection and bone involvement. later we can treat accordingly. if its ulcer then you can take topical anesthetic or analgesic or topical steroids. if it is infection you have to take a course of antibiotics and treat the affected tooth. i hope my answer will help you, take care. if the ulcer doesnt heal then biopsy can be done...