Seriously... call your RE's office and demand another HCG test - I did IVF as well and had my levles checked four or five times after my positive test.. they also did a dating scan at 5.5 weeks and a heartbeat scan at 6.5 weeks... a couple other scans before releasing me at 8 weeks.... Tell them you are spotting pink....Good Luck
Grr.. Seriously!? To let you stress for weeks for no reason is inhumane. You can go and get a couple home pregnancy tests and perform this test on your own - just see if the line gets darker or lighter after 48 - 72 hours. It's not as accurate, they say, but in my experience, as long as it's the same brand, it's pretty consistent.