3soft shelled eggs in 24 hours

 I have 5 hens who are 21 months old. 2 are ex-battery.
Last night i went to shut up at 8.30pm and checked the coop as always and found a soft shell egg.
This morning i went out to collect the eggs about 10am and there was a shell and egg all over the 3 that were normal. Cleaned nest, changed straw.
Went out just now to shut them up and 4 were roosting on the outside perches, which they don't normally do.
Put them to bed and again checked coop and poor Sybil, one of the ex bats was just laying a soft shell egg. I took it straight out before it burst and fussed her as I've heard laying these soft shells can be painful.
I don't know what else to do for them. After advice on here i'm putting a teaspoon of lime flour  in there food everyday and i'm giving them oyster shells. i also mix yoghurt with pasta once a week (messy but they love it)
I thought i'd cured it as for 2 weeks we've had 5 eggs most days and they've been normal.
Why has it started again and How can i help my babies? 

I know, it's disheartening. 
there was another soft shell today so it's at least 2 of mine.
I have cut their treats down too as the neighbours love to think of their scraps going to a good cause and i was getting enough to feed 10 hens!
 :blink:

Hi, sorry for jumping on board, I've 4 ex-batts, had them 6 weeks or so now so they're probably 19/20months.  1 has laid everyday without fail, 1 has only just started laying, 1 still isn't laying and 1 lays either a soft shelled or very very thin shelled egg, usually white in colour. They all seem fine & healthy, I was wondering if this is because they are ex-batts? They have ACV in the water, access to grit/oystershell, only other thing is the one who has laid everyday is the only one with all her feathers (although the others are beginning to catch up bless em') Presumably if they need to grow feathers, can this effect the quality of the egg?
Thanks!

The British Hen Welfare Trust were we got ours from said that the ones with the least feathers wont lay straight away as they need protein/calcium to produce feathers and eggs and can't do both at once.
There was another soft shell today but 4 normal so hopefully their getting back to normal. It seems that they go in a cycle with this soft shell thing and i'n going to start noting when it happens but as i said in my original post i do everything i've been advised too! :blink:
Thank you for the post about Davinova C i haven't heard of that. i give the ACV in there water at the moment so i'll try that. Guess you shouldn't mix the two but my Aggie will be disappointed, she goes made for ACV, the old soak!!lol

The British Hen Welfare Trust were we got ours from said that the ones with the least feathers wont lay straight away as they need protein/calcium to produce feathers and eggs and can't do both at once.
There was another soft shell today but 4 normal so hopefully their getting back to normal. It seems that they go in a cycle with this soft shell thing and i'n going to start noting when it happens but as i said in my original post i do everything i've been advised too! :blink:
Thank you for the post about Davinova C i haven't heard of that. i give the ACV in there water at the moment so i'll try that. Guess you shouldn't mix the two but my Aggie will be disappointed, she goes made for ACV, the old soak!!lol

I don't normally mix them but only use Davinova once in a while when I notice the shells are getting a bit on the thin side.  I don't like to dose the girls up too much as a rule.

As they get older the shell quality goes down hill, so thin shelled, light colored, rough shells. Can also produce soft shelled eggs. Mycoplasmia can also produce soft shelled eggs.
Speckles, who is 6, produces thin shelled white eggs, use to be brown, and Pecky will lay soft shells sometimes due to Myco.
All 3 girls eat grass which helps to absorb the calcium.

Have just picked up a soft shell egg from the Coop  7 Hens so no idea which one laid it . Had hens since October & never had this before .   Advice please .