How To Treat Swelling Of Ganglion?

The problem started a few years back.

I think is started with this:
I was recovering from a cold, and one night I fell asleep with the air conditioning on. the AC was situated that it blasted all night on the back of my head. The next day I woke up with pain in the joints of my cranium, and the muscle insertions in the back of my head. The pain was intense but no fever, just the pain. everything passed away over a week or two.
Now every time I am exposed to cold weather, water (swimming in the ocean), or AC especially in the train going to work. I get this pressure-pain in the back of my head. The pain it intensifies when I bend over (lean over) . This symptom lasts for a day or two and then it goes away, The longest i had it was for 4 days and then it went away. To me it seems I developed a sensitivity to Ac or cold climate, and its very annoying. Even the AC vent in my office triggers it. This is the only symptom i have. No facial pain, no fever, nothing but this pressure pain that feels like it would be inside the scull. When I lean over the pain intensifies and it seems to attach it self to the left year, balance bone.
I went to see an ENT and he told me that this is not really in his area of expertize. He checked me and he said that the ganglion were a bit swelled . Who do I need to see, how do I get rid of this thing?