So from reading your previous post and now this one, it shrunk a half an inch in one day? No, I don't think that is normal, but hopefully it keeps shrinking so you won't have anything to post about soon.
You're only 15! your body is still growing and will be for some time, 5 inches at your age is fine, normal. A guys body doesn't fill out until well into his 20s.
dude.. you should tie a string around your penis and connect a 5 lb weight on it... works like a charm... just make sure you do it for 5 hours or it wont work though