I have these very very tiny black bugs that move slow and don't fly but they bit so hard and I leaves a red mark but doesn't itch. What us this and how do I get ride of them?

I would guess fleas first, but they don't move slowly. They hop and if you catch one they are nearly impossible to crush.
Where do you live?

They might be a type of mite that requires blood for reproduction or a type of tick. You get your house thoroughly cleaned out with professional help, call a bug guy to tent your house and gas it. Mites and ticks carry a plethra of diseases and sickness.

If you want to keep them away afterwards, then make sure everything gets cleaned regularly, dust the house because dust is mostly made up of old skin cells and mites love to eat that stuff, wash your bedsheets much more often, every once or 2 weeks. If you wore the same t-shirt for 6-10 hours a day every day, wouldn't you assume it ought to get washed more often? Same thing with bedsheets, because your body sheds skin, you fart, you drool, you cough, sneeze, scratch your head, maybe eat in your bed.

Oop sorry, this was a way old post.