there is no real technical difference between 15 and 16 lbs... actually when you read all the spec online about a ball, those are off 15lb balls. i wouldnt go too light to like a 13 because at that weight the cores become pancakes in all balls.
if you are really not feeling well, the best thing to do is just take a break but there is no real difference between 14-16lb balls. as for the ball, if you dont mind spending the money the mutant cell is a nice even rolling ball and it has some surface to it which would help to compensate for the fact that you will start to throw it harder... if you just want a cheap ball to try something i recommend the columbia freeze to everyone, hands down the best performance to price ball out there!!!! you could drill 3 of them for less that $400 and you could play around a bit with weights and drillings.
