Barotrauma

Ears, sinuses, lungs

Barotrauma is the most common freediving injury, and the most preventable. It's pressure outrunning your equalization.

ear squeeze     equalize late, feel pain — ascend
sinus squeeze   congestion and depth don't mix
lung squeeze    too deep, too fast, too tense
if it bleeds    stop diving, see a doctor

When to call it

Blood, ringing, dizziness, or chest pain after a dive is a hard stop. Not a "one more try".