Spider mites ?
Just checked my tomato plants and found several pots full of little red/yellowish spider like bugs (teeny tiny). It has poured most of the day so soil is very wet. But on close examination you can see these little bugs moving all around on the soil. I had posted pic of some of the leaves last week and people indicated issue with environmental stress ( pretty vague reply but a reply none the less thank you). After researching I think the yellow dots on the leaves and these bugs are spider mites
But what is the solution?