Nexplanon and pregnancy

Hi everyone, after having my daughter in September or 2014 I got the nexplanon implant. it has been fine for almost three years and it is due to be changed in November of this year (so in 4 months). I'm not sure if the symptoms I'm experiencing are from the hormones of the implant maybe wearing off or pregnancy. my breasts are very tender and I've gone up and full cup size, I'm bloated and have been a little dizzy when standing for too long. I've also had what seems to be a short period twice now (after not having a pd for almost 3 years). I took a test today and it was neg. Help please?