What Causes Brown Discharge After Having Intercourse?

Hi there, so we are trying to get pregnant so I am trying to be extremely conscience about what my body is doing. I took ovulation tests on Sunday the 11th, Monday the 12th and Tuesday morning. Sunday and Monday were positive and Tuesday wasn't. We had sex both Sunday night and Monday night. Ever since Tuesday last week I have had a bit of discharge...brownish and light, yesterday it became more prominent and still brownish. Should I be going to see the doctor or is this normal? Please help.Thanks, Katherine