Dark brown blood for 5 days during period!?!?


I just got started on Clomid and for the next period I had 5 days of dark brown bleeding. I am usually a 2-3 long period that is super heavy. Took a pregnancy test at 20 dpo and it is negative. Any guesses? My doctor wants me to do blood work to see if I am pregnant, but that can get so spends.

Help please