A bad guy injects Daredevil with a drug that enhances sensory sensitivity. For a normal human, this would be confusing and nearly overwhelming. For Matt, it's hell.

A gentle touch feels like a gunshot, and Matt can't even understand what anyone is saying to him because everything is so loud and he can't tune it out. Foggy/Claire find him in his apartment, crying and unable to move because of the sensory overload, and try to figure out what to do, but basically Matt just has to ride it out while his friends helplessly watch.