If they free range she probably is getting what she needs, the feed store normally carry grit. It wouldn't hurt to put it out there. I delt with sour crop a few months ago. Lots of different ranges of diahrea. Best time to check the crop is first thing in the morning to see if its flat.. I knew nothing about this condition until I came to this site and figured my hen was blocked, she would sway her neck around and then it was explained to me she was adjusting her crop. It went from blocked to sour. Sometimes if you gently squeeze her crop and smell her breath you can smell its sour, not always though, that's my experience. Lots of vomiting. We're your hen has fluid coming out of her beck suggests she may have sour crop. It's a yeast infection and can but not always travel through there digestive system and out the other end resulting in vent gleet. I do believe, depending how severe and long it's been. Not sure if both are always are related. I could be wrong on the vent gleet.