What causes bloating and gas that is hard to pass, and hangs around for hours after meals, in the lower left abdominal area, but also mid-back area?

Feeling gassy...: Feeling full of "gas" may reflect malabsorption of food (like gluten, lactose), intake of poorly digested food, or choosing foods known to promote gas (beans, fizzy drinks). Sometimes its more complicated--a stomach emptying too slowly, bacterial overgrowth syndrome, delayed intestinal function, partial obstruction from any cause, infection, rectum problems, and pelvic pathology outside the gut.

Agree with all of the answer but will add that non alcoholic/non caffeine fluid intake is also very important. A high fiber diet without adequate fluids depending on your activity can cause all of your symptoms. Drink 80-100 ounces per day, more if you do any strenuous activity like exercise or work. And if eating high fiber don’t take fiber substitutes as this can make things worse.