I'm wiping for 10 minutes after a poop, help me?

[mianeko]

I eat a good amount of fiber I think, and I excericss everyday for an hour (track, biking, etc...) I poop 1-2 times a day and a typical poop for me is 7 inches. Recently I've been having excessive gas and after a bowel movement, I have to wipe for 10 minutes! And there is still poop! The only way I can really clean it out is to shower, but I can't take a shower while I am at school! (I'm only 13 years old!) Before this incident, I'd just wipe one time then continue with my day. But recently I have to wipe so much...I don't know why. How can I reduce the amount of time I spend wiping?! PLEASE HELP!