calf muscle

Hi, I seemed to have hurt my right calf muscle running 3 days ago. ( I have been running for months) I woke up yesterday and my right calf is very tight, it hurts to walk on.
It hurts starting from under my knee to midway down my calf.
I am concerned b/c my mom will soon be having surgery for an injury that started in her calf.
Please if you can give me an idea of what I may have done.
I think maybe I just pulled a muscle?? I haven’t worked out since. Now I am wondering maybe I should to losen it up? I don’t want to hurt it any more than it does. I hope you can help. Thank YouJayme