What Cause Severe Pain In Leg?

Good afternoon Doctors! i have 4 days ago a really bad pain in my right leg, i cant stand up, only for 2 mins, cant go to work or even to doctor, the pain coming from between calf and over the calf like strong muscle scramp, so i cant really blend my leg , and when i stand up , 1 min ok, than i start to feel my leg getting heavy and painful (strongley) after i get back to bed , all pain is gone. ( i feels like trombosis but cant believe im 25 ys old man) so the mostly pain generated at other side of knee, ( not knee pain, knee is fine) the blend area, and after starting pain calf like feeling up with blood but cant go out it self. PLEASE HELP PLEASE ROBERT LONDON