Hello First of all I want to tell you that there is a membrane between thorax ( chest ) and abdomen . When you eat something ( rather I will say overeat then stomach dilate and it presses the membrane ( diaphragm ) ,hence person feel pain in the shoulder joint on left side because the nerve supply of joint and diaphragm is one and same i.e phrenic nerve. Now main question you feel always bloated , fullness, pain on left side and constipated all the time . Try raising the head of your bed about 4 inches with blocks . It also might help to avoid eating or drinking for 2 hours before you lie down. To control stomach acid one should not drink drinks with caffeine in them or eat chocolates or greasy or oily foods , avoid alcohol. When you feel such type of pain take some antacid but if pain is severe , you may need drugs like pantaloc- D once or twice in day. As you mentioned that pain develops immediately after eating , so avoid overeating as this is the root cause of bloating , pain , fullness in stomach. While for constipation take high fiber diet . Still constipation present take phenophthelin tablet one or two depending upon hardness of stool. Plenty of water also helps . At present in my opinion no need of any tests. Only these upper mentioned measures will help . Still no relief then consult a Gastro-enterologist and get his opinion. Hope this information will help you.