You have been able to run miles earlier with recent complaints of chest pain
and fast beating heart which you didnot get relief after taking anxiety medicine with an addition of gaining weight. So you need to check for High Blood Pressure
and exclude Diabetes Mellitus
as you have gaining weight even with regular exercise(running). If excluded Check you Lipid Profile
and ECG for any problems of Heart and even TMT to exclude Coronary Artery Disease.