It probably isn't shingles for several reasons. One is, shingles are really itchy (also sometimes really painful). Two, they come on your trunk at least initially, not your leg. Three, they are usually symmetrical on your body, like a fern branch.( If you were to get them on one side of your spine you would usually also get them on the other.) Four, they don't usually happen until you're past a certain age.
But just for your info, you said "it cant be shingles i have had chicken pox." (You didn't mean because you had the chicken-pox vaccine, did you?) If you have had chicken pox, you probably should know that having had it does not protect you from shingles, it only keeps you from getting chicken pox again. Only if you had been vaccinated against chicken pox (before you ever got chicken pox) are you free of the risk of shingles.
Anyway, don't freak out. Even if you had shingles (which you really sound like you don't) they are no death sentence. Many people just get them once and it isn't particularly painful and they never get them again. If you are specifically worried about shingles (possibly because you know someone who does get them and finds them painful?) next time you're at your doctor's, get a chicken-pox vaccination. The doc will tell you that it is not guaranteed because you've already had chicken pox, but there might be some preventive value in doing it anyway.
Don't be scared. Our skin can get lots of this or that and it is NOTHING 9 times out of 10. You are young, likelihood of this being anything is very low. See if it goes away. So, I have to ask this . . . do you have some anxiety sweetie?