Hi There, I Am Trying To Get Pregnant, I Had

Hi there, I am trying to get pregnant, I had my period 14 dpo to brown/red then got lighter until17 dpo, I had a very very faint positive on 11 do but neg after that and of course got my period. But now I have mild cramping, backache and my breasts feel fuller?? I tested today and it had a faint line but could be an Evap line??? Just wondering what could b causing the cramps only a couple days after period?