pregnancy question

so I took 3 test and waiting til Thursday to take a 4th. my first wa negative and the other 2 showed very faint lines to the point it looked like it wasn't there I have irregular periods so it is hard to tell when my next one will be. Monday last week I threw up for the first time in 10 years since then when ever I get nauseated I have diarrhea. Is this normal or just wrong thinking it could be related to pregnancy?