Low pth level, hypercalciuria, cancer??

I'm a 31 year old female. I've had kidney stones several times since the age of 21. I recently had them and the doctor sent me for a CT scan. Abnormal results. I was sent to a Urologist. They did a 24 hour urine that came back with abnormally high calcium. So now I'm on a low calcium 2 week diet. Oh and there was a PTH blood test that came back very low. It was 6 and normal is 10-65.  My blood calcium was supposedly normal. I asked the lady on the phone what does a low pth level mean. Her answer is "I don't know". ARgh! I am having a lot of bone or joint pain. My throat feels like I have a constant tickle and feels swollen all the time. I have a little cough all the time. What can be wrong??

I have read that cancer associated with hypercalcemia has a very poor prognosis. With 4 kids, this scares me more than anything.

Any info out there?