Mouth Ulcers

1.I am 45 years old male and suffer very oftenly due to mouth ulcers. These are yellowish in colour, occurs due to some allergy mostly because of extrme cold chilled water/soft drink.
2.It reaches in throat area also.
3.Color of ulcers is yellow but skin all around is red.
4.Cold and very hot liquid/food do not sooth these ulcers but luke warm has very soothing effect.
4.happens almost once in a year or some times little early or later, takes 15-20 days in getting relif.
5.Suffering since last 25-28 years but in recent past i realised that is is happening due to unknowingly consuming cold/ chilled liquid.
6.Once homeopath given some medicines which i dont know but there was relief for two three years.
7.I sleep late but not more than 6-7 hours.
8.Sensitive to heat.
9.Taking treatment for anal fissures whenever there is problem.
10. Please suggest me some medicine.