What Causes Cramps And Tissue Like Discharge With Clots Inspite Of Birth Control Measures?

I was on birth control for almost a month i was having weird side effects if thats what they were, i was having un protected sex throughout the month, after the 2 week i started having little. Cramps and going to the bathroom frequently the. side effects kept getting worse i would faint here and there ect.. so like at the end of the my 3rd week.the cramps started getting a little. Worse after little piece of tissue looking. Things started coming down so i decided to stop the pill that. same day i stopped it i had horrible. Cramps they wouldn't go away so later on that day i felt like i got my period or something so when i went to the bathroom a pinkish greyish looking ball with like blood clots around it and little pieces of these tissue looking things came out i got scared and then alots of blood came out and with these little piece of pinkish looking blood clots. the cramps continued until the next day not as bad but the bleeding stopped and then later on at night the next day i got my period. Could this have been a miscarriage?