Missi I dont' know if this will help, but I had that w/my runner ducks a couple weeks ago, found some "soft-shelled" eggs, I bumped their ration of oyster shell & added some extra greens (chopped mustard, collards, cabbage, lettuce etc - even pulled some clover & dandelions from the yard) & it seemed to clear up after that. I really dont' know what caused it. My ducks are young; yearlings, they just started laying. Haven't seen any soft shells this week though, so maybe it's just them getting used to it. Tomorrow I'm getting some gamefowl feed & boost their protein level too---weather's been so bad they haven't been able to get out much. I only free range when I'm here to watch them; otherwise they have to stay in their run.
Welcome Tryals & Turbodog, lots of great info on this site for sure-
Darn it, it's just pouring down rain again right now---we'll be getting webbed toes ourselves before we know it! Have a good night all!