"won't straighten out" sounds as if one's leg is stiff and in a bent position.
"too elastic" sounds as if one's leg is loose. These symptoms appear to be in contradiction, but due to the number of questions you've asked, it appears as if you may be in distress. Best to go see a doc to examine you and ask more details in order to best help you. Can't do that in the net. Info is too limited.