I have a 3-week-old grade 2/3 ankle sprain. I have pain and repeated bruising in my calf with no new trauma--as my ankle gets better my calf get worse?

Hematoma. Depending on where the bruise is you may have a hematoma secondary to muscle injury. Worst case scenario is a blood clot in the leg which should be looked at on an immediate basis. Either way, it's a good idea to seek follow up care for that as soon as possible.
Possible DVT. See your doctor about the possibility of a deep vein thrombosis secondary to your injury.