Pain after peeing (updated)

Rachel
Edit: Went to ER because I started getting dizzy, lightheaded, and felt like I could pass out at any moment. Turns out I have a severe bladder infection.
Admittedly, I may have been holding it for too long because I didn't want to get out of bed til I absolutely had to, but for a while after my first wee this morning, I had a very sharp, pulled muscle type pain. It was right about where my panties hit, halfway between belly button and hip bone. It's still achy and sore, but not nearly as bad, an hour later. Should I be concerned?