Problems when doing curls

I have been looking around for an answer to this question and have seen similar posts, but not exactly what I am looking for. I am 21 years old and have been working out on and off for about 7 years. Most recently I have been working out regularly (every day). When I am doing curls (barbell, dumbell, and preacher) my forearms seem to wear out and force me to give up a lot earlier than I need to. I am trying to tone my biceps and can't accomplish anything because my forearms wear out way before my biceps. I get a burn in my forearms on the inside very close to the inside of my elbow. My forearms are in very very good shape, and have been since before I started having this problem. I was wondering if there is something I am doing wrong or if i have some kind of injury. They only hurt during these exercises as the set gets to the end. I really feels like I am working my forearms more than my biceps, but I want to make sure I am not hurting myself and confusing it for something else. Thank you for any help

Well, for one, your body needs rest days to recover from the non-rest days... and two, you aren't training biceps every day are you?  Training everyday can lead to injury and/or overtraining.

Thanks for that info toolman, I will bear that in mind, but regardless of the amount rest I have I am still experiencing this. I took a three week break and came back and on the first set I was still having this problem.

If I were you, I would just take some time off any isolated bicep work, and just work them out through rows/pullups/deadlifts.  This should help take some stress off the forearms, but still develop them at the same time.  If they still hurt while you are doing those, I would talk to a doctor.