L.C.
I agree with an earlier post that it could be implantation bleeding. The urine pregnancy test is based on the level of the pregnancy hormone (hCG) that is in your urine. With the current test availible, it could take a few weeks to have a detectible level.
Make sure you get lots of water in, sometimes that can help with cramping.
Secondly, a month to get into your OB?? not cool. You might want to consider switching to an ob who can get you in same day for emergencies, and within the week for regular appts.