Your problem is typical and stems from weak forearms or uneven forearm strength. What's happening is that you're gripping the bar and putting an uneven amount of pressure on your forearms. The radial bone and the associated muscle is taking more load than the ulna and its associated muscle can handle. A lot of people call it forearm splints.
You have a few ways you can get over the problem.
1. Go to a sporting goods store and get a hand strengthener. Concentrate on using just your ring and little fingers when you squeeze the ball or the springs.
2. Plate pinches - hold 2 barbell plates so the smooth side is facing out. Hold them for 1 minute increments and concentrate on using your ring and little fingers.
It could also be your form, but stay off curls like this for a while. When you start them up again, concentrate on squeezing the bar tightly w/your ring and little fingers. That will help equalize the pressure across your hand.
2 billion dollars...sir, I'd handle my grandpa's balls for 2 billion dollars.