Info on a sinus infection, worried !:(

I am 17 years old . I have a sinus infection, Could it be from allergies? I am taking antibiotics but can the allergies make it stay longer or worsen it while im being treated? Im not sure what allergies i would have but i wanna be sure i have time to fugure that out. i've been sneezing more often than normal so i thought that would make sense. Also, I am taking azithromycin and a prescription sudafed which says that nausea may occur but mine seems really bad when i take it. Is this normal, and should i continue to take it? Should there be phlegm all the way down in my chest when i cough or is this a sign that i am getting bronchitis? Last and mostly bothersome, i am having achey pains stemming from my jaw(Seems like a muscle) that throbbing there as well. Also right in the middle of my collarbones but more on the right,i am having the same pains. I notice the pain is right in the same spot as my pulse is. is this just from the sinus infection? Some body please help, I have anxiety and these type of things make me worry. Can't afford another trip to the ER unless this is something to worry about.