Skyla problems. I need help!!

so I was on the depo shot for about 9 months. I hated what it did to my body, it made me lose my firm boobs and the size of them got smaller, I gained and lost weight constantly, and I couldn't orgasm. I switched to skyla probably a month ago. hurt super bad, and I had my period for 13 days. just stopped yesterday. it was brown in color, and on Friday I thought I was stopping but on Saturday (3 days ago) it got heavy dark brown with a little red again and the next day it started going away. yesterday since it was completely gone I had sex with my boyfriend and it's been a month since we have had sex. we had sex twice. I didn't bleed. I was fine. he did mention he might've felt the string bc he felt a small sharp pain for only a second. today I got terrible sharp pain cramps. and there was red blood. very red blood. no brown. and my uterus hurts so bad. the blood is so red and heavier. it hurts extremely bad. it comes and goes. I'm just scared of something bad is happening. the blood is different. the cramps are worse. does anyone know? thanks for the help in advance.