I too may have a swollen lymph node in my left cheek (unless it is something else) for 2 1/2 years. I think it is due to my upper left primary molar (tooth) which I have had work done on. Apparently the work didn't correct the problem, even though the tooth does look better on X-ray! I know for a fact that the tooth is cracked and there is a small crack in the root of the tooth. Have you had any trauma (like a punch) to the left side of your face? Did you ever have to get a root canal for a tooth on the left side? You may have a crack in a tooth and you may have to get it out. If you haven't had any root canal work done and you have had a blow to the left side of the face, have an endodontist check your teeth on the left side.
I didn't realize there were nodes in our cheeks. I do know that we have saliva glands there. Perhaps you have an infection or saliva stone lodged causing discomfort.
Take a flash light, open your mouth and pull your cheeks away from your teeth. On the upper right and left part of the cheek you should see a small "bumps" on each side. Those are one set of saliva glands. They should appear similiar to one another.
There is a dental forum here. I would take photos, sign up at Photobucket.com and then post the images to the forum-if that is what you consider.
If not or as an addition, I certainly would make an appointment with an oral surgeon or at least a dentist.