Have Painful Ulcers On The Tongue (mainly Top At Foremost

Have painful ulcers on the tongue (mainly top at foremost edge),plus my gums are very sore. I have been using mouthwash BENZYDAMINE, and sometimes, salt water. These ulcers come and go at intervals of about 3/4 weeks. Only treatment that seems to get rid of the problem quickly is NYSTAN (Liquid drops)This gets rid of problem quickly....about 3/4 days.......but it will return after about a week.
A n ulcer at the corner of the mouth is being treated with FUCIDIN.....but does not seem to be effective.