What Causes Pain On The Calf After Food Poisoning?

After a case of probable food poisoning two days ago, my lymph node in my groin was very swollen and extremely painful. the pain and swelling have gone away now, but my calf muscle on the same leg is now very painful. its hard like im flexing it, but im totally relaxing it. its very hard and painful to walk. what could be causing this and what should i do to treat it?