I know you are looking for info, but it is tough since we don't know you or your body.
To answer your last question, yes, being pregnant can cause you to bleed after sex. Your cervix becomes all swollen and filled with blood, knocking is more likely to cause bleeding than when not pregnant.
As for the discharge, I have no idea. I beleive I have experienced what you are talking about before (while not pregnant), but the nasty taste in the mouth is very tell tale of pregnancy... For me anyway, I couldn't get the metallic taste out of my mouth until the third month.