Hello, I read your message and understood your medical problem. Before I into conclusions, I need to see the skin lesion so please send me a photo of your ankle so I will be able to give a proper advice. It can be shingles too but in this case, the rash usually is vesicular and follows the road of the nerve. Vaccination does not always protect. It can be caused by other infections as well viral, bacterial and fungal infections. Allergies may cause contact dermatitis in this area and blow up the rash. The type of rash identifies the cause and this is why I need to see photos. Considering the location rheumatoid diseases also need to be thought about.  The possible diagnosis is skin infection and it can be treated locally with specific solutions or ointments depending on the cause. If the situation is serious you may need to take drugs orally. Hope this is helpful.