Sounds like the flavoring chemicals are what are bothering you. I know someone with the exact same issues (with those same liquids, as well as anything from China) and it took her a long time to find liquids she could vape without problems. She ended up vaping Halo's line, Vapor Station's line (flavoring comes from India), and Ecopure's line without problems. It turned out it wasn't the PG or VG at all.
Maybe buy some samples or ask members to buy small amounts of them in the Classifieds? You can also look for people selling those vendors liquids in those threads. http://www.e-cigarette-forum.com/forum/classifieds-swaps/
Good luck to you.
She said she has already tried just pure VG and had the same reation.