Hello!
Wear an ankle brace or an ankle band to restrict movements and weight bearing.
Do not wrap it very tight or do not move your affected ankle joint excessively.
Keep it elevated on a pillow during your sleep and apply ice packs and also take NSAIDS such as ibuprofen or naproxen.
If your pain and inflammation continue beyond couple of days you have to follow up with an orthopedician.
Take care!
I don't think you need to wrap it, just ice. But are you sure it's a tendon? I mean it could be, but what makes you think it is?