Unless the leg is oozing (when the fluid can be sent off) you should have blood cultures - blood is taken and then any bacteria in it grown and identified so we know what antibiotics to give you. I assume someone has properly looked at the leg to exclude the possibility that this is an insect bite that has become infected.....
If the leg remains swollen when the skin appears normal I would also consider an ultrasound to check there isnt a deep vein thrombosis. Also check for diabetes and blood supply to the leg.
Discolouration can be persistent so if the skin is intact and you become symptom free you can be patient.