What Causes Coughing, Congestion And Shortness Of Breath?

Hi my name is ally. I have been experiencing these weird cough attacks. i usually get them once a month but today i got it twice. I was in third period and then once when i came home and was trying to take a nap i woke up and was trying to breath and was coughing like crazy. I spit up some mucus but that doesnt really happen. i can usually feel the cough coming when i get this sharp feeling in the very back of my throat. it feels like i have sand in there and my mouth is really dry. I dont know what this is either, i have never talked to my doctor about this or anything. I dont know anyone with this kind of thing happening to them. the cough usually happens when im in school for some reason. it has never happened at home until today. the cough usually last for 3-4 minutes and during that time its really hard to breath and my stomach sucks itself in. i need help