White Spots on Leaves (pics inside, possible thrips?)

I had these spots about 2-3 weeks ago. They haven't gone away and I'm almost starting to think they are spreading!

Getting quite nervous, and would rather figure it now then when my plants start having issues.

I have searched for bugs many times now. I can't find anything but what appears to be nats flying around!

Could this damage be caused by nats?

Not all of my plants are showing these issues. Only 3 of the 8 I have flowering!

The grow is indoors in a cabinet. The soil is Fox Farms Ocean Forest. I believe I gave myself nats by not allowing my soil to dry out enough before watering.

Please any advise be greatly appreciated + rep

I am having this problem pretty bad at the moment, all the plants in my flowering cabinet have these at the moment, there are not bugs like mites etc, but there are tiny, and I mean tiny little white/beige coloured creature on the underside of my leaves. If you look very very closely, you will see them, and they are normally only one or two per leaf, it's not like there is an infestation or anything, but the damage is severe.

I thought is was a Nitrogen oveload, as I am growing Hydroponically, but it seems that this may well be a bug issue. Shit.

Bud