Talk to Dermatologist on Hair Loss (Alopecia)

I've been experiencing alopecia areata for the past 18 years. Initially, it appeared as small patches in three different locations on my scalp. After getting treatment and using various medications prescribed by multiple doctors, the patches disappeared. However, a patch on my crown didn't cure and has been expanding over time. Now, my crown area has almost no hair, and the remaining hairs on my head are thin and low in volume. I also have some hairloss patches on my arm. What's the best way to restore hair and reduce hairfall?