Hi Nancy, you don’t have to be double jointed to hyperextend joints. I hyperextend my knees and elbows past negative 10 degrees. I first learned I could do this form my physical therapist and my doctors. i never realize I was doing it. All my joints pop too and it’s actually subluxing. Sounds like you’re describing you joints doing that. Even sounded like you had a complete dislocation that you managed yourself. For me it started in my ankles, TMJ/jaw, and my patella on my left knee. Now it’s almost every joint my body from my thumbs to my shoulders to my big toe. I would try to find a dermatologist that knows something about connected tissue diseases and maybe she can order a skin biopsy for you, and then from there you can go to an endocrinologist. If you could find a genetictist that would be even better. Do you have the stretchy skin? Check multiple places on your body. It only needs to be 1.5 cm or greater. Doctors prefer the volar surface of the wrist. Do you have abnormal scaring? Like thin, white, transparent, stretch marks? I hope you can also check out the videos on here that dr. Diana made. They are full of wonderful info.