Short of breath at rest. feel the need to take deep breaths at rest. it doesnt get any worse when walking/doing activity, what could this be?

Physician visit: Your physician will evaluate you for the cause. Cardiac and pulmonary diseases are among the possible conditions.

Physiological: Agree with Dr. D that you should visit a doctor at your convenience. However, the need to take deep breaths, like sighs, is physiological.

Short of breath: Please see your doctor ASAP. Getting help as soon as possible is safest and surest route to good health. Heart or lungs possible issues. Peace and good health.

Anxiety?: If the problem is not affected by activity, it may be from anxiety especially for one at your age. Has there been a lot of stress lately?