What are the common causes of intermittent abdominal bloating/distention?

Constipation, etc... A person who feels bloated (in the tummy) off and on is not normal, especially if the bloating is new. A doctor can evaluate to figure out the cause. Problems can be due to eating things the person cannot digest. Some parasites cause bloating. More serious causes of bloating include a build-up of fluid in the abdomen due to kidney disease, liver problems, heart failure, abdominal cancers, etc...
OK. This is constipation! a hi fiber diet, 20-25 grams of fiber per day, drink 80-`100 ounces of non caffeinated, non alcoholic fluids daily and increase your fluids if you do strenuous work or exercise. Do not use harsh laxatives. Excess fiber in the face of inadequate fluids will cause bloating and constipation.