Being late

I'm late on and been having tummy pains sick pains and I couldn't eat without feeling I'll and ovulation area pains on and off what could it be I done a poundland pregnancy test and said negative but I'm only 4 days late could it still be pregnancy but just to Earlie or if not what else could it be please help me figure out or is it worth going to the doctors please help guys thanks guys in advance xx