Doctors Question??????

I have to get a hearing test. I had a screening couldn't hear two of the 4 frequenies my doctor said its promptly no big deal could be wrong. But the i don't think its from loud noise because you would have heard the other two frequencies. I'm 17 i have no trouble hearing how bad could this be? should i be worried i get a hearing test in two weeks but it scares me to death :(