I have sliding hiatus hernia and take one capsule omeprezole each night after meal till chest pain is resolved. Can I take omeprezole twice a day?

Yes, but. This can be taken twice a day or double the dose to 40 mgs taken just at night. This will probably give you good control. That being said there are some long term issues that might arise with continued use of this drug, dug as osteoporosis, anemia and electrolyte abnormalities. These are not assured, but occur with more frequency. At your age you might consider operative intervention if you are requiring medications to control your symptoms. You also should consider all the other maneuvers to prevent replug such as weight-loss avoiding eating before bed and avoiding fatty meals, Before any other treatment medical or surgical.