I know cotisone is very efective with mouth ulcers. There are gels like Kenalog but this would not work due to the location of the ulcers. A tablet swished around the mouth could help, it may be worth asking just your gp as it should not hurt anything else. Just a sugestion as I have had them my whole life before cancer.
Tony

lyph node positive 10/08
Parotodectomy 4/09
Rad six wks 65 grey
Pet scan clear 03/10 no primary
Pet 01/10 base tonge primary
CT 3.5 Tumor 01/2010
radical tongue reconstruction
with forearm flap 2/10
severe Trismus 06/10