Our 4 Year Old Grandson Was Lying Down Watching TV

Our 4 year old grandson was lying down watching TV just before bedtime last nite, after his bath, and when he sat up I noticed his hands were completely without color and cold. He had been in the bath tub for several minutes and the water had cooled. But this occurred approximately 30 mins after his bath. After he moved around for a few minutes the color return but they were still cold. Also, he has been complaining about mild stomach pain for several days. He has had the flu and bronchitis and we attributed it to that. What do you think?