It sounds like maybe the cyst is trying to shrink now due to loss of hormones, etc. from the delivery. That can be really painful, so I've heard. If that's the situation, I do think that probably there does seem to have to be a certain amount of "tough it out" time so the cyst has time to shrink, etc. and I don't know how risky it would be to go back in and remove it at this juncture, although I'm sure you could talk about it with your OB.
The other issue is that you feel you aren't being heard. I would take one more stab at your doctor. Go in for an appointment and communicate your concerns and ask what can and will be done now and in the future. I would hate to see you have to switch doctors at this juncture, but I suppose going into someone for a second opinion wouldn't be a bad thing either.
It really does sound awful so I hope you get it figured out! Hang in there!