I keep finding this tiny beetle on bed once a day
Try searching google for images of black carpet beetle, see if they match what you have. The image I'm looking at has already been enlarged a lot, to it is hard for me to see additional characteristics. The UK Entomology website has a fact sheet on managing various types of carpet beetles. If you are still uncertain, bring it to your county extension office, identifications are free.
Bessin, UK Entomology