It may not be because of the food
Just check his tempature (100-102 f) is the normal temperature
If it's more than that that time he will feel tired
If temperature is normal then if he had too much walk and all that time he will feel tired
Hi, 104 degree Fahrenheit is very high. Please take him to a 24 hour facility now itself if you can otherwise first thing in the morning tomorrow. Please get a blood work done to know the exact cause of fever and get him treated accordingly.