nostr:npub1ypfcrd4k5ryzlcg8jmdvgrlk29ladfe27z7c2aaq8lvmks6drwqqautsp5 sounds like you're on the right path already! Mast cell activation syndrome is specifically mentioned in my GAPS book as well. The reasoning is that the gut lining is damaged and lets in too many undigested particles into the blood stream, causing allergies and other problems like MCAS. 

I'm doing the GAPS introduction diet soon, which is specifically to heal the gut lining. That diet consists out of mostly meat broths to start with. I wish I had my own chickens too!