In an episode also titled Barry Allen receives a literal and figurative "shock to the system":
Since the title can refer to a few different series, here are the dominant "stories" for each: [S7E2] Shock to the System
Meredith continues to hide her pregnancy and subsequent miscarriage from Derek as she struggles to get cleared for surgery. She eventually breaks her silence when she realizes she can't handle his reckless driving anymore. In an episode also titled Barry Allen receives
He chooses to save Iris from the Mirrorverse but does so with computer-like logic that harms his friends and causes Iris to suffer a seizure. Seeing the damage his logic has caused provides
Seeing the damage his logic has caused provides the emotional "shock" needed to break the Speed Force's hold and return his feelings. Other Shows with this Episode Title
Barry gains the ability of "speed-thinking" thanks to the Artificial Speed Force, but it begins to strip away his humanity, making him cold and calculating.
In this emotional aftermath of the hospital shooting, the doctors struggle to return to "normal."