Period

Soo I had my period like two weeks ago then had unprotected sex the next day after I was finish wit my period and after that one  week later I get light bleeding for 3 days.is that normal?could I have a chance of begin pregnant........but too after those 3 days of light bleeding I've been having lots of discharge it's clear white an Been feeling dizzy and nauseous for the past 2 days......I've even took like 3 pregnancy test they all come negative and just took one again to make sure and it was negative.  
What can I do? Do I go to the doctor to make sure I'm ok ?