Ivy,
We had those "mites" thingy in our flat too, but that was like a couple of years back when we just move in.
It seems to have "disappeared" after a few months. These creepy creatures were so tiny and you would have missed it unless you take a closer look. I only discovered it when I was doing some cleaning. When I first saw it, I squeezed it to death and left some marking on the wall. And as I was cleaning that mark, I was shocked to discover more of it to the rest of the wall. Quite scary to see the "outbreak".
As I was catching it, I also managed to catch some bigger ones, which were actually long-legged spiders.
I think those "mites" could be the off-springs of these spiders.
But the good thing is that it seems to be in 1 room only (heng ah), and I have a feeling that it is coming from a cupboard that we have bought from a warehouse clearance. The wood quality of that cupboard wasn't really good and I always blame that cupboard for bringing in these creepy thingy.
I have tried closing all windows and door, then sprayed insectiside in that room, "sauna them" for almost an hour and still didn't managed to exterminate all.
Slowly, after weeks of dusting, I'm quite relieved that its gone for good. I killed quite a number of those spiders and it could really be the cause of it if those are really the off-springs.
Since then, I have made a habit to dust all walls, ceilings and corners.
But dunno if your mites things are the same as mine though.
Btw, I just killed another "long-legged" spider yesterday.
Sandy,
take care. I guess the company from anyone in the family would greatly comfort your grandma. Please take care and be strong.