apricot oil or almond oil and just start with a teaspoon.
You can find these two oils in the health food store usually in the health and beauty isle. You can eat it too don't worry.
I found that these oils were lighter and don't give you as good as "pull" as heavier oils like flax, but are great to start with or if you just want to change up.
Keep trying and make sure you haven't eaten before pulling. That may make a difference too. I've had to hawk up some nasty stuff coming down from my sinuses.
Keep trying and let us know how you're doing.