Thank you for the query.
Such swollen and painful calf is most likely caused by veins thrombosis
. You can perform simple test to confirm this diagnose. Please straighten you leg in the knee and flex your foot down. If the pain appears in the calf, veins thrombosis is possible.
I suggest you to visit your doctor and have blood work, CRP and D-dimers checked. If D-dimers will be elevated, Dopplers ultrasound
Please do not neglect such symptoms as veins thrombosis can lead to pulmonary embolism
Hope this will help.