I missed my period, so I took a test and it was positive... 3 days later my husband and I had sex, and I was bleeding for 4 days, and now I took another test and it's negative.. Did I have a misscarraige?

Possibly, yes.

You took a pregnancy test, it was positive, now it's negative. Yes, possibly you had a miscarriage OR either one of the HPTs is incorrect.

I took 2 tests positive, and 4 negative.. would it had happened beause we had sex?