WHAAAAT

OKAY. So, I'm on birth control for the first time ever. So far, so good. So, the placebo week for the pill comes around and still no period, so I try not to worry, my body is probably adjusting. SO MY PERIOD IS 6 DAYS LATE and I'm starting to worry. But today it finally comes, so yay. Then, out of nowhere, I start getting horrendous cramps, like cramps I have NEVER had before. I got sweaty and hot and dizzy and short of breath because I was in so much pain. The pain lasted for maybe 30mins-1 hour, then I start feeling better. I go to the bathroom just now, and I pass something out of my vagina. It didn't hurt, and I have NEVER passed something like this. I WILL SPARE YOU THE PHOTO, but it is about the length of my thumb, looks like tissue. Color seems pink, but it's also my period so I don't know. I feel better, BUT WHAT THE HECK WAS IT? I'm a little concerned. I also feel a little sore on my left side when I stretch a certain way, but it's bott bad and I worked out yesterday so it's probably unrelated but WHAT?! Please help me, I have no jdea what's going on, I've never been on BC before?!!!