UPDATE:

The Gabapentin seems to be working well. I have not had any cramps now for over 2 weeks and my limping has improved.

One thing i have noticed recently is that my lower hamstring just above the back of the knee seems swollen when i straighten my leg. It seems to start at the crease behind my knee and then go upwards in the shape of the hamstring (if that makes sense). Any ideas what this could be?