Negative Pregnancy Result :(!?

Started clomid 50mg 2 tablets a day 9th march - 13th march after not having my period for 7 months since i stopped yasmin pill. clomid ovualtion calender said i should be ovulating 18-23 and i had on 18 , 21 , 23 without protection. Doctor told me i should get my period 3 wks after i finished clomid so i was supposed to get my period between yesterday and the day before. i had yesterday and i got sudden pain in the abdomen during it which ped after a minute. when we finished and i went to the toilet after peeing i had some blood when i wiped.... what is thaT? it was only that time that i had blood and it was a little. i just did pregnancy test but it came negative..