My Cat Constantly Coughs?

For the past week my cat has been coughing like crazy! it is summer and she is shedding so that's what i assumed it was like a hairball but nothing comes up every time. Do you think it is something she ate. She just was coughing and fell over. Then she got up like nothing happened. She is just lying down right now looks ok. I can not get to a vet now due to the time.