What to do about an infected blister?

I have an infected blister?

• I ran a 5K a couple weeks ago (around three weeks ago) and got a pretty large blister right on the ball of my foot under my big toe. It popped from when I walked on it a little later, and drained, and I thought that was the end of it. But as the days have been passing, the spot where the blister was began to hurt a LOT. I can't put weight on it. It's very swollen. There is a brownish-blackish dot forming close to where the blister was on the ball of my foot. It's very itchy. Sometimes, my entire foot hurts from having to keep the weight off that area. I know it's infected, but is this serious? Should I wait a few more weeks for it to heal over? What's going on? Please tell me anything you know about an infection with my symptoms!

• Answer:

  Have you been putting antiseptic cream on it? A blister is safe while it is still intact, once it pops it is open to infection. If the area around is red get a permanent marker and mark around the red area, have a look at it the next day and if the red area has increased in size get to the doctors the infection is spreading. I had to do this with my finger once and left it to long ended up in hospital and nearly lost my finger. Get it treated now and avoid some pain. Only a doctor could tell you and a simple case of antibiotics will prob fix it