i hate loud noises

one time in my old school the tiles on the floor started popping due to the weather. the first one popped right beside me if my memory serves. it shot high up and fell before cracking. i didn't even know what was happening at that point of time. now my therapist says i have ptsd since i am deathly afraid of loud sudden noises. i have no idea what shes talking about, but i am terrified of loud noises. i think i went into a panic attack because of it once. my head was hurting there was ringing sounds and my eyes were blurry and i couldn't breathe. the same thing happened today. but my friend warned me beforehand, so i dont understand why i got frightened. why am i like this? why did i still get frightened? there were so many classes in my school so why mine? i dont mean to be offensive or anything. i want them to stop but i dont want to tell them about my situation. i dont want to seem pitiful or and attention seeker. i hate this. i cried earlier, why ami so useless?