Do you have adequate ventilation? (In Texas I'm sure you do- but you didn't really say.) If you have a fan running and not enough ventilation, it could just be blowing the nasty air all around without getting rid of it? I use pine shavings in the coop and no droppings board. Every morning, I scrape the roosts off, turn the pine shavings over, and open all the windows. If in an hour when I go back to the coop- if it still smells a bit, it's time to change the shavings. Also- I noticed a big change in droppings smell when I switched feed brands. I just installed a droppings board yesterday, which I plan to scrape off every morning. I'm hoping this will allow me to change the shavings less frequently. If you use sand, how long has it been since you changed the sand? You could have droppings dust build-up that's causing the smell. Just some things to think about, I guess.