I had a minimal amount of brown discharge, I had felt sharp cramping pain on the right side of my abdomen, my breasts are tender

I think I may have experienced implantation cramping last night and this morning. I was at work and had a quick sharp pain of cramping all over my lower abdomen. I thought I was starting my period but It is not due for another week or two. I am on the birth control pill but have recently switched to a new brand. I have not been taking it the same day everyday but within an hour before or after the normal time. Anyways later in the night when I showered (I clean myself out downt there with water when I shower) I noticed that I had a minimal amount of brown discharge. Then this morning there was nothing and after I had taken a shower I had felt another sharp cramping pain but located only on the right side of my abdomen and I have not yet felt that pain again or any other cramping. Also my breasts have begun to be tender. Me and my boyfriend had unprotected sex on the 14th of Nov. He ejaculated in me and the day after I had very light brown stretchy mucus like discharge. Which I think was my ovulation time and maybe I had a small tear from the intercourse. I was wondering if I should take a pregnancy test or when I should take one? Please help!