Sorry about your rooster. Does he seem to be feeling and acting normally? Is it cold where you are? Does his comb color improve at times? The blue color can be from a lack of circulation or lack of oxygen. Some roosters may have that issue if they are overly excited or cold, or dehydrated, but a heart or breathing issue should be considered. Watch him to see if it improves. Make sure that he is drinking plenty of water. Electrolytes might be good to use as well.
Maybe the heat is stressing him. I would give him some Poultry NutriDrench 2-3 ml orally, or electrolytes in his water. Let us know how how he gets slong.