Chest Tightness and Frequent Burps.

Hello Doctors, I am having chest tightness wen I lye down Flat or stretching my left hand,dis issue wer der for almost 3 months. Consulted ortho dey said issue is bcaz of poor posture & spasm. 1 month back consulted cardiologist & took ecg, echo,tmt,chest pa & lipid profile,except cholestrol & BP all the test comes out normal. Taking bp Medicine. Total cholesterol is 196 and ldl is 121.8. My cardio said no heart issues just lifestyle changes & weight reduction will help to cum out. Day before strday to get 2nd opinion consulted another cardio he chkd my old reports & me then commented de same all r normal nothing to worry. 2 days back in nite I have got chest tightness & sweat. Visited cardio again for tightness he again said nothing to worry. Getting frequent burps after eating food & walking also. Can hear sound & all from stomach while lying. My worry is why am I having chest tightness all the time. Bcaz of this bcum very anxious too, it is gastric or cardio issue.