When I had the cyst pain (yes, they sure can cause pain no matter what the docs say) I originally thought it was Diverticulitis which I had once before.
Causes the exact type of pain,
nausea, etc. However,as I mentioned, you may be a little young for that . .. It's little pockets in the bowel that become inflamed/infected. The left ovary is very , very close to the part of bowel that Diverticulits occurs in so it's very difficult to figure out where the pain is coming from .