What do you think this is?

Courtney

So i usually get my period every 28-36 days and my periods are usually so heavy i need a tampon and 2 pads at the same time. I had unprotected sex 13 days ago with my partner. I was suppose to start my period 5 days ago but i started spotting and having mild cramps 2-3 days ago. I get maybe a few drops in a pad/day. Its more noticeable when i wipe and barely anything in the toilet. Its hasnt gotten worse then it has been. It started off brown and i thought oh here comes auny flo it was brown for about 2 days then went to pink and now its back and forth between brown and pink and its been red one time today but just as quickly it went back to brown and pink. Could i be pregnant? Does this sound like implantation or does this sound like my periods going to full on start. My cramps are usually way worse than this. Let me know if youve experienced anything like this and what the outcome was. Im planning on taking a test tomorrow if the bleeding is still the same.