Soft spots/ thin shells on Egg

[The Coastal Chicks]

My 3- one year old hens I adopted last week have been laying. The first few eggs were "normal" today I had one with a soft spot and it did not feel right after I cracked it to look inside the shell was paper thin.
Question#1 are those eggs ok to eat? #2 is this a transition egg from the move? I have oyster shell out and kept them on the same food.
Other ideas?

and yippee they found the nesting boxes!!!!

 

[cletus the rooster]

usually after a move they stop laying so that is amazing! the eggs should be fine to eat. are they on laying mash? or i would try some yogurt or something with some calcium to harden up the shells