Runny poo & loosing tail feathers

[my girls]

Am worried about my chickens, unfortunately the lady that was supposed to look after my girls when we went on holiday didnt, so they went with little water & food for one week, now a week later after proper feed, they are doing runny grey poos, also there are a lot of feathers in the coop, their tail feathers seemed to be dissapearing.

Have had my chickens for 1 year with no issues as yet. Although another chicken has also started walking backwards which is a bit weird.

Also they are not laying at the moment.

Help.