An infection in the bone and in foreign material in the bone is very serious. Such infections can continue for months and cause damage to the bone and surrounding tissue. The foreign materials could break down and cause pain and other problems. The infection can go into the blood and cause sepsis. This is life-threatening. Antibiotics should be started now and probably continued for several weeks if not months. It is possible he has had this infection cooking along in the bone for sometime and it is now just coming to the surface. This means it is now about to spread very quickly. This happened to my brother. His hip replacement became infected but didn t show any outside signs until he went into shock and was taken to hospital by ambulance. He was lucky to survive. Keep trying to convince your friend to see the doctor. He will eventually end up there anyway and in much more serious condition if he waits. Hope this helps.