Haven't had a normal period in 6 weeks

Two and a half weeks ago I had two days of very light bleeding mixed w brown on and off. I didn't consider it a real period, it wasn't consistent and wasn't five days like normal. 
Just now, a week before my period is actually due I had blood when I wiped once or twice and nothing else. What's going on? Pregnancy test was negative, so I'm not pregnant from anything before two weeks ago. I did however have sex two weeks and one week ago, so maybe this is implantation? Either way my periods seem to be messed up. Should I go to the gyno?
I don't have endo or PCOS. I was checked for both two months ago