Miscarriage?? Pregnant??

Me and my boyfriends anniversary was september 18 and we went horseback riding... I was getiing pains in my stomach a couple of days be4 that day but I have past stomach problems so I just ignored them. So I went horseback riding and I was fine untill I got in the car to go home. Well it was a long ride home (about an hour) and I was getting these really bad sharp pains in my stomach and I thought I was having my period but I wasnt due until the 28. When I got home I checked my underwear and they were full of blood. I never bleed like that be4. Later on that night me and my boyfriend tried to have sex and it hurt sooooo bad I started to cry... Well I was bleeding for about 3 days (still heavy)then that forth night it was gone the fifth day it came back in the afternoon when I got up it came back but not as bad. The 21. The 22 me and my boyfriend had sex and he ejaculated inside of me again. And I am gettin weird pains can I be pregnant again or is it tooo soon? And do u think that I had a miscarriage? Please help me understand what hapened too me...