SOS - BROWN BLOOD

Help!! So this morning I woke up with a small amount of brown blood in my underwear. I thought it was my period but my last period was from Jan. 8th - 15th. The last time I had sex (with a condom) was on the 29th. I guess my period could be early or maybe it's possible it could be old blood??? I put a tampon in for a few hours and when I took it out it had a small amount of very dark brown blood on it. I need some other girls opinions on what this is! Thank you :)