Error in site feed

This feed was working and then I changed my theme and it no longer works. It doesn’t work in any theme. I get the error message “error on line 21 at column 72: Opening and ending tag mismatch: img line 0 and a”. Not quite sure where or what this is or how to find it.

My feed is http://fitnesssquadron.com/feed

I would appreciate any help.