Hello~Consulting Dr Google is the worse thing a person can do, I know, I have been a expert at it and always scare the bejeebers out of myself.
As to bone cancer, I would not worry too much about it. I would first see a chiropractor, you may very well have some misaligned vertebrae that are causing your pain; he/she will take some x-rays, study them and then go over the results with you. After a few treatments, the pain should start getting a lot better.
As to the Bartholins cyst, I would say that since it hasn't grown or changed any, there is nothing to worry about. Have you had it looked at before? The reason I ask is if you have and were told it is not cancer, then it won't be cancer, these cysts are benign.
Try not to worry, I know it is hard, but it only makes things worse; it also can make pain worse.