Possible pregnancy

So I haven’t had a period in over 2 years and I finally got the okay to take provera and had a prover induced period on July 25th. It lasted 11 days and it’s been 2 weeks since I’ve gotten off of it. However for the past 3 days I’ve been spotting brown and dark red blood only when I wipe and occasionally tiny drops on my underwear. I am at a lost because I am not expecting my period to come for another 3 weeks let alone naturally. I’ve also been very dizzy and nauseous but with that I’ve been having sharp pains and also some shoulder pain and am afraid maybe I could be experiencing an ectopic pregnancy. I am not sure if maybe you are suppose to bleed heavier with ectopic so maybe that’s not what it is. I am also maybe thinking of it being implantation or ovulation bleeding . Please let me know your thoughs