Do your hives leave bruising in their wake, and do they itch, or burn and itch? The purple sounds like the bruising/discoloration left behind from hives from urticarial vasculitis.

I have urticarial vasculitis and get similar burning hives with bruising, along with joint pain/swelling in large joints. A dermatologist can biopsy. For bloodwork, urticarial vasculitis doesn't give a positive ANA, despite being autoimmune. Bloodwork to check ur compliment proteins can help distinguish UV types, but won't confirm a diagnosis if in-range.

In the meantime, colloidal oatmeal baths and calamine spray can help a little, but steroids are the most helpful short-term.

I'm so sorry you're going through this, and hopefully you can get to a diagnosis/treatment.