I have a rash on my arms which have fine bumps and itches

Hello Anon

Thank you for writing.

Without an examination you may not be able to tell what is going on.

You may be having an allergic reaction to something. You may also have Brachioradial Pruritus - you can read more about that here (cut and paste) https://www.empowher.com/skin-hair-amp-nails/content/brachioradial-pruritus-intensely-itchy-arms

If this does not clear up in the next few days, see your doctor. I hope you feel better soon.
Best,
Susan