Lack of stomach acid can cause random pains because, with lack of stomach acid, ulcers are more frequent, bacteria that would have been destroyed by the acids, are causing the pain. It can be caused by improper chewing of food. It would be you hate something bad or not properly cooked. Lastly it can be due to Chronic Candida, this is yeast that thrives inside anyone with low stomach acid and it causes a digestive pain. If it persists it advisable you consult a doctor about this.