I've had quite a scare

Monday morning I had to leave work to go to an urgent care, because I had extreme pain in my lower abdomin, the pain was making me dizzy and nauseas. When I got there they said it might be appendicitis or kidney stones and sent to the ER, at the Er they ruled out both, they took blood and xrays the only thing they found was elevated white cells and I had a low grade fever. Now I'm a generally healthy woman aged 30, the only surgery I've ever had was toncilectomy when I was five, but my Mom died at 36 of leukemia, my grandmothr now has it, and four other females on the same side of my family have or had breast cancer. They decided to do an ultra sound and I asked the tech if she saw anything she said she couldn't tell me and then she left to get the radiologist which took forever. When he came in he told me that I had a mass the size of a plum on my left ovary. AT that moment I've never felt so alone and scared in my whole life I just started crying. All my family and friends were at work and couldn't get ahold of anyone. They took me back to the Er and called my gynecologist who decided to admit me for more tests, I came home yesterday with no answers. I've just been told that if the pain comes back to return to the Er so they can remove the mass. Very comforting huh???Has anyone else had this kind of experience, my dh thinkds I should get a second opinion. I do still have some medium pain on and off, but I don't know how much pain justifies going back. I'm kind of scared considering my families history and the fact that know would give a direct answer about anything. Any adivse would help. Thanks for listening.
Becky