Injured my ab area during a workout 6 months ago. pulling feeling around belly button. mri showed tiny umbilical hernia. is this why i am in pain?

Depends: If you are only having limited discomfort at the umbilicus then the hernia is likely the cause. If you are having a variety of discomforts and intestinal symptoms then should see your doctor for evaluation to look elsewhere as the hernia is not likely the cause.

Possibly: Generally speaking an umbilical hernia is usually painless but if you have pain and have a documented hernia it could be the cause and you should see a specialist. You may also have pulled or strained a muscle and that can cause the pain as well.