What Causes Throat Infection?

my throat is a little scratchy and i keep spitting the phelgam, however now nothings coming out but i keep having to spit. i usually take a z pak to get rid of the infection but usually i wait until it gets worse and i actaully start hearing weezing. do you think peniccilin will do the job if i react quickly to it. i am 18 years old 6 foot 175 pounds. i used to have assma but its been gone for a decade, i smoke cigerattes and about every 4 months this happens to me