signum I know what you're talking about. I think its called clairsentience. I know because I have it too. Its just like yours, but at a lower level.
Groups are the worst for me. It reminds of that scene from the Matrix 3, where Neo is getting bombarded by rays of energy.
I do the mental draining thing too... removing negative energy from my body and it works but only for a short time.
I did a google search yesterday and came across this link, take a look.
Clairsentience I've just gotten into researching all of these myself after years of suffering.
Those energies that you're feeling that go away when you notice them... they maybe your spirit guides in a different dimension. Just a thought, maybe you should look into it.