Several years ago, when I was 16, I started having pain. Generally a few hours after I ate, worse at night, severe pain in the mornings.
After a few months of that, then several weeks of intense pain that left me completely bedridden (I could not uncurl from a fetal position) my father finally took me to the doctor.
The doctor ordered a lower GI done, stones or polyps showed up on the ultra sound. It was actually rather funny when the person found them, she went and got two other people because she wasn't sure what she was seeing. Here I was 17 at the time, 110lbs and never been overweight.
I was put on antibiotics because the doctor thought that a piece of stone might have tried to pass but became stuck, thus causing an infection. I probably should have had surgery.. my father refused.
So I'm at the same place you are. I have to watch everything I eat. No fast food, no fried greasy foods, absolutely nothing that could set it off if I can help it.
If I ever have another acute attack, it's coming out.
Since you have a large stone, golf ball size?!!
you will need surgery. It's a matter of time until you get an infection if that's not what is causing your pain right now. See a doctor soon and get something done about it, you do not want it rupturing or the infection to spread.