Check under the leaves with a magnifying glass for mites and eggs. The mites will look black\brown and they are very hard to spot. If you see any small spots..keep youre eye on it for a minute to see if it moves.

The easiest way to check for them is to leave the plant undisturbed so they get a chance to make webs and then spray the plant with water from a fine mister. The water clings to the webs and makes them easier to see. As your plants are in flower... go easy if spraying them to avoid water affecting the buds in a detrimental way (bud rot). I would never reccommend spraying plants that are in flower, only if absolutley necessary or if you want to identify a problem.

You've got many options if it is spidermites but whatever you choose, do it quick because their rate of reproduction is very high and they can devestate ur plant given the chance.

If u have the cash and they are available, I would recommend introducing some natural predators of spidermites. If u can get hold of any ladybirds (ladybugs...whatever), they do a fantastic job of eating the spidermites and do no harm to the plant.

Without pics.. its very hard to be sure of what it is tho so get some pics uploaded.