Do you see bits of web? Are there pale speckles on the tops of the leaves? = MITES.
If you are not past week 3 of flower, mist lightly with neem oil, allow to dry, check for any apparent leaf damage, mist again. The leaves should start to appear just a touch shinier than previously.
Get a little breeze going in there and drop your max temps below 75. This slows down their breeding.
Get 2 pyrethrin bug bombs. Set one off immediately, then set the other off in 2-3 days.

This should knock them back and buy you time to harvest.
Then after harvest, SCRUB your grow room inculding all pots.

This method works for other pests too. But mites are really and truly evil.