Spotting a week before period..

I had a very light spotting a week before my due period (2/12) it came out brownish when I wiped. Thought it was my period coming. My husband and I had sex the next morning and saw there was a little bit of blood only on the head, he had a condom on. We only used a condom due to the fact I thought my period was coming. Later on the day I spotted then I decided to go ahead and put a tampon in. Changed it an hour later and only had a few brown spots, not even enough worth using tampon. Didn't get anymore spotting after. Tested a week after (yesterday) came out negative but still no period. Wondering if it was an implantation bleeding or what. Right now I'm having cramps so maybe my period is coming but that spotting is a first for me.