What can i use for 2nd degree sunburn on my lips?

I was in a rodeo riding my horse April 25, 26, and 27. On Monday the 28 is when my lips started blistering and being painful. It has now been 8 days and i still have blisters and a little pain. Plus i have lots more rodeos coming up including this weekend and i dont want it to happen again. what is the best lip balm to use to prevent this.