If you haven't actually seen any insects such as mites, etc, then I would suggest to see a doctor who can diagnose the problem. Insects are visible. There is no insect that is invisible. The next classification down from insects is bacteria which could be invisible. But that is not something I can diagnose nor give you any advice on. It sounds like this could be a health issue? Lice, scabies, etc? Difficult to say, but my advice is to NOT spray anything for insects until you know exactly what the insect is. Seriously, it could be many different things.
Here an article I wrote on Insects you can't see that bite - https://www.epestcontrol.com/articles...
If you can visually see insects then get a hand lens and see if they look like mites or chiggers. You can see pictures on Google.
If it is mites or any insect, then yes we can help. We just need to know what it is and have a specific target pest.