My tendons seem to tear at the drop of a hat & they take aaages to heal. I've partially split the tendons in both middle fingers & lately I seem to have torn a bit on the outer right-hand-side of my heel. I was doing a hamstring stretch when I first felt it. Now I can't do that stretch again until it's fully healed or it tears again. Am I missing out on something nutritionally perhaps? It didn't even feel like I was over-doing it - I put my foot on the kitchen counter to stretch out the back of my knee & my ankle tore a bit. Any ideas?