Fissure Question?

I had fissure for probably 4 years already. I went to a doctor and he told me to eat healthy , take sit baths but it doesn't seem to help. I read that if you have minor or moderator fissure then it can go away with that and sometimes cream. However, is it possible for someone who has fissure for 3-4 years for it to heal or is it impossible? Doctor told me most people have the 6 or 12 o clock and i had the 3 o clock one.