Mine did this last week, sooo bloody annoying. I have had a peeky inside and cant see anything that would cause it other than the fact that is a cheapy brush (but I love it) So I figured I'd wash it, not much to lose as it wasn't expensive. So after i washed I left it for 24 hours and then used my hair straighteners on the lowest they would go to just flatten it again and voila - it's like a new brush.
I wouldnt hae done this on a more expensive brush, i'd be too scared to ruin it lol.
When my L&P skills are better I will invest in a better quality one but atm this one does me fine.
hope you get it sorted, you'll need it for that colour fade on your toes!!!!