Why every time i swim in a pool/ocean i feel this pressure on my chest as if i cant breathe? i do have chronic gerd which i am taking medicine for, so i do feel this sensation consistently when im out of the water, but amplifies when im in?

Exercise induced bronchospasm or vocal cord dysfunction should be considered. Aspiration may exacerbate these conditions. Avoid caffeine, heavy meals two hours prior to swimming. GERD medications may be adjusted. A virtual consultation with Healthtap is available. Watch for signs of shortness of breath and vomiting.

Being chest deep in water exerts more pressure on your chest than does air. I can't tie this symptom to gerd, though. I assume your exercise tolerance is otherwise healthy with no cardiopulmonary problems. If not, undergo a cardiopulmonary evaluation by your MD, or cardiologist.