Light spotting after sex

Ashley
Hubby and I are TTC for past three months. I had what I thought was my period because it came right when period was due however didn't have any cramping and was only 3 days as opposed to 5 and the flow was light instead of heavy like normal and it was light pink to brownish instead of bright red. Ever since then whenever I have sex with my hubby I start spotting light pink only when I wipe the next day. I took a test sat and thought I saw a faint line and then took one today and didn't seem to see anything. Been having headaches and am tired more then usual. Anyone have this?