Yes, the temperature definitely could have something to do with it.
When chickens drink large amounts of water (like to cool off in hot weather) their droppings get extra-watery. I don't know for sure about the throwing up, but I think it could also be caused by them drinking much more water...
Did the problem start before or after you put things in their water?
Do they also have plain water available? (Plain water meaning nothing added to it.)