Something is out of alignment. See a good chiropractor.
As you had your tests done some years ago when your problem was intermittent, it may be worth doing the tests again now that you have the problem all the time.
It could be to do with your liver and gall bladder, or a muscular skeletal problem, tendons or muscles, especially as you had the pain come with physical activity.
May be a good idea to be referred to a physiotherapist.