I haven't heard of "Hard Edge" either, but it sounds just like what I've felt in the pit of my stomach since I was a teenager,
I always referred to it as a "petrified log" in my stomach. As far as anxiety causing stomach issues - abso-bloomin-lootly!
I've suffered from Colitis (years ago), GERD (still), IBS and a myriad of issues from the large colon to the top of the esophogus
which is all -- all related to stress. The only way I've been able to handle it is some form of exercise (which right now is
exercising dogs) and "mindful breathing" which has helped immensely, not only with the stomach issues, but also with
chronic pain and anxiety. I've found over the years that I hold my stress in my stomach and shoulders. It causes pain in
my shoulders, but causes illness in my stomach/esophogus. Oh, writing and speaking things I'm grateful for every day
is a big plus for me - turns me right around.