I was really rooting for you. Are you taking any hormones (ie, birth control pills). I had an ovarian cyst (not sure what kind of cyst you have) but it was pretty darn big and caused me much pain. We were even tossing around the idea of surgery, but instead went with the pills. Well they worked in shrinking it, and then I went off of them about 6 months ago -- because I had gained about 15 lbs. It was a trade off actually -- do I want to retain water like a camel, or do I want the cyst to go down so I'm not bent over in pain. Late last year the cyst reduced to almost nothing -- my doctor couldn't even feel it in the "internal" exam. I went off the pills. At my last appt. he still couldn't feel the cyst and I've been pain free for 6+ months.
I know your situation is probably entirely different, but I would think with a cyst of that size that hormone treatment would be an option -- or surgery.