Not sure what’s going on

I’m on the pill but had barely started into a new pack when I started kind of getting symptoms. I’ve had more cervical mucus daily than I ever have had, but not doing anything different with my days and recently I’ve been nauseous, feeling weak and tired, constantly either hot or cold ( never a nice temperature), headaches, and lower back pain. I want to dismiss it as the flu, but because of the abnormal discharge I just don’t know. HELP. I read somewhere I shouldn’t be seeing any symptoms within 4 weeks (besides missed period). Any in-site?