Pile is starting to smell like ammonia/urea and I have no browns, help

My pile was started in mid April and steaming since March but I haven’t been adding enough browns for how much grass clippings I’ve been adding and it reeks today. I stir my pile before I add clippings and would add saw dust between layers and stir after since it was mostly browns on the bottom but now I’m out of browns do any of you have any suggestions?