Thank you for submitting your question. The most common type of rash to appear around the ankle area is eczema( dermatitis). It is typically red and itchy. You can treat it with over-the-counter hydrocortisone 1%- apply to the area three times a day, followed by a moisturizer.
Another possibility is fungal rash, although this typically involves the toes and heels, and causes cracking and peeling of the skin.
I hope you find this answer helpful.