My 9year Old Son Had An Appendectomy 4 Days Ago.

My 9year old son had an appendectomy 4 days ago. The surgeon explained that it was very bad an gangrenous and that the area was walked out. Day 2 he woke with a severe pain in chest and back( central at his sternum) explained as gas. He appears to be recovering well however today he mentioned he has blurred vision ( object shook from side to side- his words) about 3 times tonight he is very cold and clammy to touch. We have to have bloods taken tomorrow again LFT's as they were abnormal before. What could the blurred vision and cold and clammy skin indicate??