You need to use baby wipes when you clean your backside; and then apply Analpharm 1% ointment.  Analpram is a perscription ointment that also contains an Praximine, and anastetic (generics for Analphram work well also).  You need to do this every time you go to the bathroom.  It will get better in a couple weeks.  It took me years to figure this out.  Good luck!

http://www.drugs.com/mtm/analpram-hc.html

I find ilex protectant paste is by far the best product to relieve and prevent a sore bum, what is more commonly referred to as butt burn

www.ilexhealthproducts.com/usd/products.asp?cat=1