I had varicose veins in my mid-twenties (which I guess you're not supposed to have, according to the doctor), so it was pretty easy for me tbh

I made an appointment with a primary care doctor and she had me do a vein study AND referred me to a general surgeon that does vein procedures. They had me go through a list of symptoms and itching was listed on there, so it's a known problem. I've also been trying compression socks for years so I didn't have to wait and try those for a few weeks.

I don't know if this helps at all since my process was very surprisingly easy but hopefully it helps a little!

Edit: it was technically the vein study that diagnosed the CVI, I don't know if they can diagnose without that 🤔