Hi, I banged my left knee about 5 weeks ago whilst getting into the car, it was very painful at the time, a lump formed just above and to the left of my knee. This lump was painless and caused me no problem. We went away for the weekend and took park in an Hill walk, that was quite steep and left us all aching afterwards. Later that night I felt me knee going tighter, this got quite worse by morning, as the day went by the swelling got worse with redness spreading down my leg. The morning after I went to a&e they diagnosed cellulitis, I have been on Ivs since monday, redness clearing but still angry and sorness around area of lump, could this lump have caused my cellulitis, why is the lump not responding to Ivs.