Hi and welcome to HCM.
There are few most common causes of ankle swelling. It can be related to your hives
as a part of allergic reaction
but much common are heart, circulatory and kindey disease. So you should check these organs first. If this happens afte rlong standing then this is probably resulting from venous insufficiency
and yous hsould consult vascular surgeon. Till that try to avoid long standing, lay with elevated legs, or use some of elastic compresses. Wish you good health.