10 days late and negative pregnancy test.

I've been having occasional little lower back stinging feeling but i might be so worried that i notice every little thing in my body. I've also felt like my stomach is bruised in spots for no reason, and at times bloated. Today the nipples of my breast itched and hurt a little afterwards and it went away. My period was supposed to be here Feb.18th and took a test the 25th that came out negative, I'm also irregular but not THIS irregular. What should i do? Has anyone gone through this?