I've got 2 Barred Rocks and 2 Red Sex Links. They are 18 weeks old. One of each breed has started laying on a daily basis. In the last 2 days, I've noticed 1 of the 4 has diarrhea (don't know which one). It is brown...no blood. All 4 act healthy. Since they just started laying, I've yet to start them on layer mash...will do this week. Treats incl. clover, black sunflower seeds, grapes, greens (spinach), peas....stuff they've had for a couple of weeks. All 4 were checked and had clean vents....no dried mess. Any clues?