Yup had the same side-effects. Mine turned into a cold eventually. What really helped me was always having a bottle of water while vaping, take a few sips in between pulls. You lose a lot of moisture from vaping. Also 100% VG shouldn't be an issue, if anything it should produce less throat irritation. VG is however heavier than PG making your inhales a little more "cumbersome".
Initially my side-effects were
1) Acidity/stomach aches
2) Irritable throat which turned into a cold eventually
3) Dizziness (I didn't realize that I was taking in a lot more nic while vaping than smoking, the nic OD caused dizziness)
4) Constipation
All of the above eventually went away after 1-2 weeks.
I had night sweats, a cough that brought up loads of gunk, the runs (for about a month), and having to clear my throat constantly, in addition to stomach aches and dizziness.