The groin pain and walking issues began my intro into my hEDS. Finally found out it was coming from a hyper mobile SIJoint extending to meet unequal leg lengths created from a hip ball joint replacement. Walking around for 4 years with that created damage in the other hip ... It also stretched the Illiopsis ligament that connects the back to the pelvis. The fix was prolotherapy that tightened the loose ligament and keeps the SI Joint mostly in place. I say mostly because it does still move slightly out of place but a knee to the chest realligns the joint. I will also add that the ligament was totally tight before it overstretched. Lying along the side of the bed and dropping the leg will stretch that ligament.
Hope you find help ... Regenerative Medicine is one place to try