My guess on that is, it's totally possible for things to be broken/ revert you back to whatever theme, because if it's code isn't just right.. it's considered "broke".
I don't usually put a theme up, without testing it first on the localhost.. so maybe try using the "default" feed urls once..also try, adding back whatever codes that were modified heavily..and see if that problem persists..
With a theme I was working on, and me not good with PHP at all, period..I spent a few hours fixing what I missed, removed..over-added and so forth.. damn. Time consuming sigh..but, it's part of learning hehe.. I love it!