The vinegar can be controversial. Two Crows and others recommend it, while others do not. The probiotics are always good, but if using plain yogurt, do not overdo it. A tsp per day would be enough. Sour crop is very hard to treat, and there does not seem to be any official professional information about it, only opinions on what has worked for some people.
Thin shelled eggs sometimes can break inside, and are a medium for bacteria to grow up into the oviduct. Make sure that she gets layer feed and some crushed oyster shell available to help her shells. Even with that some chickens can still have thin shells. I have a hen like that who suffered internal injuries, and some viruses can affect the shell gland, causing thin shells or other abnormal shells.