Startle REALLY easily??? I mean like, I startle soooooooooooooo bad... even the slightest noise I hear or movement I see will startle me to the point that, if I am standing up or walking, I will stumble... or completely fall

It is so embarrassing. I mean, I have heard people say, "everybody startles" and I know that's true... but most people don't fall down (and possibly get hurt) when they startle. Walking down the sidewalk and hearing a horn blow - doesn't make normal people fall down. It does me. Seeing something unexpected out of the corner of my eye makes me hit the ceiling. Being in a room and hearing a door slam down the hall... someone taps me on the shoulder... I could go on and on... all these things are things that most people don't think twice about... but they are things that haunt me every day of my life.
My startling is so bad, that I am afraid to do... really anything that requires me to have to stand. And I can walk with crutches, but I hardly do nowadays... just because I don't wanna fall and 1) be embarrassed and 2) possibly get hurt... so now I pretty much use a manual wheelchair everywhere I go, so I don't have to worry about falling when I get startled. *sigh* But I know because I am not using them, my legs are just getting weaker and weaker... I know, because on the rare occasion that I do try to walk, it is harder than it used to be.
And I am scared that one day I won't be able to walk AT ALL and will be confined to a wheelchair.
Are there any medications for startling? Is there hope for me??