Hello, you should understand that stomach pain occur due to numerous reasons like gastritis, food allergies, food poisoning, constipation, lactose intolerance, gastroesophageal reflux disease, ulcers, indigestion one of this might be the cause for your problem. Based on the history you have given it might be due to gastritis/ indigestion for that my advice is- avoid having untimely eating habits and eating spicy or oily foods which can cause gastritis. Also drinking coffee amd tea frequently while working also aggravates this condition. And you should know that alcohol and smoking also known to cause gastritis. So the main thing I suggest is to stop all this. The most important thing is to follow a healthy diet which should include green leafy vegetables, fruits and berries which are rich in fibre.take fresh fruits instead of taking it in juice form, since the waste formed while making juice consist of fibres which will be beneficial for the gut, so prefer fresh raw fruits. Take lassi,yoghurt,buttermilk, ragi gunji instead of coffee and tea. Avoid smoked meat products. Avoid outside food, prefer only home cooked meal.drink plenty of water. And never skip a meal. Do daily morning brisk walking, yoga and meditation. If you are not satisfied consult a dietician.