Hello! Symptoms you have decribed are mostly caused by GERD (gastroesophageal reflux disease). And it can be treated by lansoprazole which was prescribed by your GP. However it is strongly advisable to perform endoscopy in case like yours as stomach acid excess might be caused also by other diseases including peptic ulcer, hiatus hernia and gastric cancer. That is why in every case of hyper acidosis gastroduodenoscopy should be performed to rule out cancer. You can also reduce your symptoms by stop smoking, avoid two hours before eating, elevate your head of the bed, avoid fatty food, coffee, acid fruits or juices. One more thing might be important. Acid excess may also occur in pregnancy. Take care