New cat owner needing advice

I just rescued a 5 month old kitten on Dec 10 2013 and when I did pet value gave  me a free bag of cat food Perfomtaince ultra  for kittens and now that I am almost threw that bag I thought would change him over to Royal Canon for nutired kittens I have mixed the 2 to slowly weine him over but today I noticed there is blood in his stool that was not there before I did this advice please

Hi, welcome to TCS!  It's nice to meet you.  I would recommend taking your kitten to the vet for a workup.

Welcome to the site.  I second the vet visit.  He could have something going on.  Dietary changes don't usually cause blood in the stools.

yes thank you he is going tomorrow