Why Does A Hiatal Hernia Cause Pain? --such As Pain

Why does a hiatal hernia cause pain? --such as pain in mid-section below rib cage, vomiting, shortness of breath, back pain. When or should I consider a procedure to correct the hernia? I find bending over to work in my garden, mopping kitchen floor, vacuuming, lifting or moving furniture/objects causes pain
Thank you for your input. This condition is limiting my lifestyle. --vanita