My 1 year old is running 102 fever and his scalp is red and sore to the touch?

My 1 year old has a fracture of his left tibia which is in his leg. I don't think this has anything to do with his leg, but last night he developed a fever and has been running a fever since. This morning when we took him to the doctor to get his cast put on, he developed this redness on his scalp and a little on his forehead. Its not a rash its just really red, and if you touch it, he cries so I ume its hurting a lot. The pediatric orthopedic doctor told me to take him to his doctor. I have an appt to get him this after to find out whats wrong. Anyone know what this is?