Suppose, you were exposed to a highly stressful incident or intense fear. You began experiencing tightness in your chest, a rapid heartbeat, shaking, an inability to concentrate, chest pain, and shortness of breath. In that case, you might be having an anxiety attack.
The attack will usually subside once you move away from the stressful incident or fear. If the attack seems to happen out of the blue, you might be having a panic attack instead. Panic attacks do not need a trigger to occur.