Yikes, that's never fun doing an out-and-back run and getting stuck many kilometers from your starting point. I've done it during marathon training to force myself to do certain distances for my long run and sometimes really regret it about halfway in when I realize how far I have to go to get back to my car or my house.

I hope whatever is going on with that leg stops bothering you but play it safe...I've always found it's better tone down the training a bit for a week or however long it takes to get the body to cooperate than to push through and really hurt yourself.