I had a guinea hen with large waddles. The girl that we lost to egg laying it was probably her first egg ever & she was so still in the coop as she tried to pass the egg. After several hours of trying the egg came out & so did her insides. Poor DD was so freaked out.
I say a guinea falls under the title of poultry & If i were to suspect illness i would treat mine same as the chickens. However, guineas never seem to get sick. They are so much more hardy than chickens! Can you see any signs of him being hurt or picked on? I do hope he gets to feeling better.
Oh man. I haven't ever had a guinea get sick either. They've gotten injured early on, like in the first two weeks, because they're fragile and crazy which is not a good combo, but never had one get sick.