Hi my 7year son has been complaining of a sore back when I looked this evening at the bottom of his spine there is a small lump which is red and very sore 2 touch, he has had 2 operations in the past 4 weeks on his eyes (don t think this has anything 2 do with it but just incase his last operation was only on Monday) he hasn t banged it as still recovering from his operation. What else can it be?