About 3 weeks ago I finished up AFF and got cleared to self supervise in freefall. The following week I made my first solo dive from a CASA (we normally jump from an Otter), and as I was going to make a second jump I got very nauseous and light headed on the plane. I decided to ride the plane back down. Yesterday I went back to jump (again from a CASA) and the same thing happened at about 12,000 feet. My instructors think I should try making a fun jump with one of them next time just to help build confidence, but I was wondering if there's any thing else I can do to help prevent this. I generally don't eat much on days I jump. I'm just very frustrated right now. I'd appreciate any advice.