Ectopic Pregnancy

I am on Implanon and have been on it for 2 years 9moths. Lately I've been getting off and on pains in my lower right abdomen. Well it went away and then came back but this time it radiates into my back when I sit down and I have been spotting for a few days sometimes it is bright red and sometimes it is almost a brown color. Could this be an ectopic pregnancy? I had a friend tell me it was and now I'm worried.