My wife had the same problems with her first e-cig. She's really sensitive as well. I thought it was because she was sensitive to the PG, but that wasn't the case at all it seems. Like adrenalynn mentioned, it's the acclimation period. It's a whole new learning process. If you vape like you smoke analogs, it's not the same.
After the first day, I encouraged her to stick with it. Now, she vapes normally and there's no problem.
After the first day, I encouraged her to stick with it. Now, she vapes normally and there's no problem.