Drowning and feeling like you can't get up

Over and over again, I get that feeling at the pit of my stomach. Like my heart is sinking, and I feel like my heart is drowning and won't float to the surface. It's like I'm not quite dead yet, but if my heart doesn't get some air soon, then I just might.

I wonder if there's some chemical imbalance in my head that causes me to constantly feel this way. For all I know, I'm just over analyzing and exaggerating my situation, whatever it may be. Everytime I think about this too much, I start to tremble.. My legs or arms get all numb and I just suddenly feel as if I'm about to have an anxiety attack. Ew.. I just feel all useless and I don't know what I can do to change this.

I just wish everything would go away

( edit 10:18 pm)
I just took a shower.. and for the first time, if I'm remembering correctly, I had a horrible shower. And if you know me, I take 45 minute showers and I probably only spend 15 mintes using soap and cleaners on myself. The other half an hour is just standing in the shower, feeling the warm water on my body. I was in boiling hot water.. you know, where it's so hot that you start to feel cold? I just felt so cold and alone. I just had to get out of the shower as soon as possible.. And great, now I can't take long showers.