Help .. Miscarriage, pregnancy , or birth control symptoms??

[10flower10]

So I had unprotected sex about a week before my period was due , but it was only stuck in and out a couple of times. ( at this time I was not on birth control) then the following weekend my period came as usual and I had the most excruciating cramps I've ever had in my life and I noticed that the blood at first was pinkish , then turned red but it had almost like tissue pieces in it ( this period is when I started my birth control called cryselle) so I was worried but my period came so I thought maybe it was my uterus shedding. My periods are usually 7 days but this period ended up only being 2 days and like a morning of 3. This is when I started to freak out because my period then became this light brown discharge which I've heard can be implantation bleeding but my period was definitely red blood ... Just super short. During the next week after my period ending my boobs have become so extremely sore to the touch and my nipples have been hurting as well and I've had mild cramping ... I don't know if these things is just my birth control reacting to my body or if I am pregnant or possibly even a miscarriage ?