I can feel an ulcer
Most ulcers heal within 7-10 days. To ease any discomfort, try:
Warm salty water rinse periodically throughout the day
Difflam spray or mouthwash available from your local pharmacy
Bongela available from your local pharmacy
Thorough cleaning of the area
Corsodyl mouthwash (one week max)
Soft diet
Pain killers
If the ulcer is due to a rubbing denture try a denture adhesive such as Fixodent to help secure a loose denture. Sharp edges can be filed using an emery board.