Could I possibly be pregnant?

My AF was due on the 26/03 and I have small amount of spotting which is a really dark brown colour , nothing like my usual AF! Before I had this I was experience more CM than I usually ever get! It was thick , creamy white and odourless! While this was happening I was experiencing cramps which weren't like the ones I usually get! The cramps were located in my ovaries.I took a pregnancy test 5 days before my AF was due and it was negative.
I've also been experience a dull ache at the bottom of my back and have been feeling Sick! 
Do you think I should test again or just wait? Any advice or opinions would be much appreciated!