sinking

A feeling caused by uneasiness or apprehension.

“with a sinking heart”

“a sinking feeling in the pit of my stomach”

A descent as through liquid (especially through water).

“they still talk about the sinking of the Titanic”

A slow fall or decline (as for lack of strength).

“after several hours of sinking an unexpected rally rescued the market”

“he could not control the sinking of his legs”