Inside my nose hurts really bad!?

On the wall of my left nostril it really hurts. Its like red and white. Its been happening for 4 days now. The first 2 days they were just annoying and weren't to bad, and the 3rd and 4th they were so painfull to the point where i started tearing. What is this? and what can i do to make it stop hurting and or heal it! Please help i'm dienggggg (: