Soft shells (again)

I have been having this problem with one of mine (I only have two hens).

Over the past few weeks she has laid about 5 soft-shelled eggs.

Sometimes she has laid 2 of them a day!

If they are not broken I rescue them and scramble them but often they just get trodden on.

So, I should give them grit right?

How would I check for worms?

Many thanks.