Don't know what to think!!

My period is 4-5 days late! a couple days ago, if felt like it was definitely on its way! Now no signs since then!! I had taken a test recently and it was negative! I do kinda have some what of a churning stomach with gas and diarrhea. And somewhat of a backache that comes and goes. I have also been feeling a little depressed and moody! But my period is nowher in sight! What are yours thoughts!?