What Causes Persistent Pain In Calf Muscles?

my right leg has been so painful lately. A very steady sharp /consistant pain in the calf area, but on the side to the front area. As I am overweight and have trouble with my knee due to that thing under the kneecap messed up and RA to boot. That I don t know if I should take this serious as to maybe a blood clot or not. The pain just grows worse daily.