dear friend, thanx for sharing your concern,
the symptoms you have mention shows that you have recurrent apthous ulcer and you are very correct. yah it is very painful.
first i will tell you what is to be done in this case then i will explain you what is the cause .
1 you can apply DOLOGEL (lignocanie baced ) on the affected area.you can apply this before food . so that you can comfortable have your meal.
2 i recommend you to take one capsule becosule daily for fifteen days, this will definitely solve your problem
now the cause for this is
1 iron , b-12, folic acid
3 very rarely Bactrial infection.
so i would also suggest you to take very healthy and nutritious diet , rich in vitamin b-12.
you get this plenty in milk and milk products, meat, egg and green leafy vegetables and fruit .
try to be stress free.
tk care thanx