Suggest Treatment For Severe Leg Pain

My 71 year old father had a severe onset left leg (calf) pain about two hours ago. He tried to "walk it off" and it hurts worse to put weight on it. He's eaten a banana, drank water and now he is cold. he said the left leg is colder than the right. I can't physically feel externally that it is colder. he is hesitating going to the local ER but I am worried.