Hi,
@Aschenherz, sounds like hyperacusis. As the others have said, it definitely gets better with time. You are just hypersensitive right now. Do try not to dwell on it, as it can make you phobic to the point you don't want to leave the house. And don't walk around with ear plugs in all the time, as it will make you even more sensitive.
If you feel panicky after hearing a sharp sound, try to calm yourself down with measured breathing techniques. Here are instructions for an easy one called four-square, or box, breathing. You can do it anywhere -- sitting in your car, on a park bench. Just go somewhere quiet right after you hear the noise, sit down and calm yourself and do the breathing. It won't take long for you to feel better.
http://www.livestrong.com/article/74944-box-breathing-technique/
I still sometimes will feel briefly panicky if there is a sudden sharp noise, like microphone feedback when my choir is singing. But I can calm myself down pretty easily now.
@glynis's advice is spot on, too.
Good luck. Really, this symptom will indeed improve. Remind yourself: It is only a noise, it just lasted for a few seconds, it will not make my tinnitus worse, it will not harm me.