It is possible that you crash dieted for which your body is not used to yet. The gas build up is likely to have caused the loss of appetite. You will require antacids. The following steps may help: - Don't skip meals, you may not feel like eating but in such conditions you should have the reduced amount in frequent intervals(i.e. 3 square meals broken down to 5 or 6 as you can tolerate) and slowly increase as you get better. Having small frequent meals will also increase your metabolism. - Reduce/ Avoid spicy,fried, fatty, junk and oily food - Avoid/ Limit drinking coffee, tea and carbonated drinks to once a day - Exercise regularly (minimum 30-45mins of cardio exercises everyday) - Increase daily intake of water to 3 liters - Avoid/Stop smoking and drinking if you have the habit - Reduce stress through methods such as yoga/meditation. - Avoid painkillers as it will increase your gastric problems at this moment. If the condition persists or worsens visit the nearest ER at the earliest.