i'm sorry i dont know much about clomid etc but i can tell you that with dd2 i had a brown discharge b4 af was due to arrive and i'd done a hpt with a bfp so thought i was going to mc. The dr told me it was a threatened mc and to come back if af didnt show up in another wk, now i know a little more about prregnancy etc i believe it was implantation bleeding.
HTH somewhat and wishing you with a BFP sooner rather than later.