Miscarriage or something else?

ive been ttc (trying to concieve) for at least 5 months now....and i also have polycystic ovarian syndrome which means irregular periods...i've had neg. test after another...and about 2 weeks ago i started light bleeding...but sometimes its light,heavy,spotty, and it comes and goes this has been goin on about 2 weeks now..and i think im ping tissue..its greyish looking...any ideas what this is?! im scheduled to go to the doctor..just needed a lil advice before i worry myself!!!