Why does my elbow hurt after lifting weights for a few weeks?!

If I lift weights for a few week with three sets of eight reps, my elbow feels like someone is sticking a needle through it. I push heavy weight to give myself a workout. I do three days a week. Chest and tries one day, back and bi the next with legs and shoulders the last. Normaly I give myself a day or two inbetween. I have good form and take my time. Is there another way to lift weights and not be in pain?