I Have What The Doctor Described As A Form Of

I have what the doctor described as a form of ulcer on one side of my urethral. The first one lasted about one month and used lidocaine, for the discomfort and it went away. Now, I have another one, but smaller. Is this normal. I am 64 years old. the doctor said that I didn't have sexually transmitted disease, I had a blood test. Plus, I am not sexually active and haven't been for 6 years. Any answers for me?