You should upload a picture.

Sorry, don't have that capability.

Do you know what rootstock it is on? If not,. Without pruning it can get quite big and tall.

Cherry tend to have canker. One way it could happen is when a tree having an open wound. Where are you located? I am in a cold zone. I do not prune fruit treesin the fall. I prune cherry in mid spring. I choose the time that there are no rain for a few days to do it. Wet and warm weather invites fungal diseades.

It's a self-pollnating sweet cherry tree. I'm in zone 6b, PA. Very fertile soil. I bought it from Miller Nurseries in NY, which has merged with Stark Bros. I tried to look it up in their online catalog to get a pic for you but they are sold out. When I bought it, it was called "Xtra Dwarf Stella Cherry Tree." Now I think they're just called "Dwarf Cherry Trees." I'm going to email the company and check with them about pruning. I wish I had saved the original catalog.

I opened a talk box with the company and they directed me to their pruning instructions which I printed out. I will prune it in winter or early spring.

Is it Gisela 5? Its dwarfing to some extent, but will easily reach 14 feet without pruning.

I'm not familiar with Gisela. It's an Xtra Dwarf sweet cherry tree - a Stella.