Update on Ailing Hen "Sweet Pea"

My hen "Sweet Pea" is recovering from her mystery ailment gradually.  I separated her and fed and watered her and she instantly went for the water drinking at least 2 bottles pretty much at once.  She started eating regular food along with some scraps from the kitchen...squash, lettuce etc.  Before this all started her comb and wattle was bright red and very healthy...it became pale and began to shrink until it is now half it's original size.  The color is coming back and hopefully will begin to grown back like it was.  She couldn't stand for a while but that has corrected itself as well.  Not laying yet but hopeful she will in the future.  The other 2 hens were not affected and are still fine and laying.

I don't think she was broody...never making broody sounds... althought this is my first experience with chickens and really don't know much...I'm doing on the job training.  lol  Any thoughts and/or tips are welcomed.

Ok more issues with Sweet Pea.  She's laying great double yolked eggs but the shell is not a shell but something that looks like leather.  I've added oatmeal and crushed oyster shell to their diet and maybe it just takes time for that to show results?  My other two are laying normal eggs.

I'm thinking I could have inadvertantly poisoned Sweet Pea...i was feeding them table scraps as well including avocado peels and I read that they were toxic to chicks.  I know she's improving cause her comb and wattle are rejuvinating and growing again instead of shrinking.  Yogurt is next on my list of feeding additions.  I truly welcome more ideas, comments!