I had brownish discharge and mild cramping....hang in there. Your numbers are not dropping and that is a good thing!
I haven't had your exact experience in that I have not been on chlomide or had IUI, but I can tell you that my Dr. never became concerned about HCG's until they started actually dropping. The doubling rule is every 48-72 hours, and its not always actually doubling, just increasing. So being that yours were 2 days apart, and still rose, that sounds like it might be ok. As for the brownish discharge, that is so common. Many of the women here have had that, and even full out bleeding and been just fine. Mild cramping is also very common. It sounds like your Dr. is monitoring things closely with another test on monday, and I wish you all the best of luck. I hope all works out well for you. Take care.