First seen on some clean washing out of airing cupboard two together. Then another found on my dressing gown , seen under microscope , they are clear and can see all insides moving but very very tiny. Seem to have a black or brown line down the middle and as an outline. Have a cat and a dog but have never seen this type of bug/mite/? Before please help as have newborn and want to get rid of them ASAP. Can't find a mass of them anywhere yet.

Sounds like psocids. Also called booklice, they feed on microscopic mildew fungi. This link from Iowa State can tell you the easiest ways to get rid of them.

Psocids, Booklice, Barklice | Iowa Insect Information Notes