I had colon resection in nov. today bellybutton is very sore and hard around it like a ball. help! what could it be?

?infection: Certainly, a delayed minor wound infection could cause hardness and pain. If so , redness and warmth is close behind. Could also be a closure suture knot, if one is present there, or even a small incisional hernia . Call your surgeon monday and notify him/her of this issue. If redness or warmth develops , or if tenderness becomes unbearable, you'll need evaluated before then. Good luck.