HELP. NEED ADVICE

Liz
Hey y'all! 
I need help! 
I'm on BC, and usually I have one and a half periods every 2-3 months. But I've just had three, the third was spotting and now today all the sudden I feel HORRIBLE. Basically all things period without the blood (yet) I took a pregnancy test last week and it was negative, but should I take another one? Anyone else experienced this before?? 
Thanks in advance!