I have what feels like a knot between my chest bones/upper stomach, which that area fills tight than ease's up, this does not happen all the time but several times a day, I have been scoped for ulcers and everything is fine, I take medicine for acid reflux which has been fine, I just feel like the doctors have not figured it out and it's miserable, any suggestions? I wish they could do a test when it's actually hurting. Thank you Shawn