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There are a few possibilities which could be going on with your goat. First I want you to look at your goat's mucous membranes (gums or third eyelid of the eye), what color is it (red, pink, pale pink, or white)? If the mucous membranes are white, I fear your goat may be anemic from parasites and is having a hard time breathing from the anemia. This will require a good de-wormer, such as Cydectin for goats. Your goat will also need supportive care, such as fluids, vitamin B complex to stimulate the appetite, and to be kept warm and eating and drinking.
If the mucous membranes appear normal, then I would recommend taking the temperature rectally with a thermometer. You can use either a mercury thermometer or a digital thermometer along with vasoline or KY jelly. If the goat's temperature is greater than 103.5 F, then I suspect your goat may have pneumonia. This will require antibiotics such as Naxcel which you can get by prescription from your vet. Also, Banamine would be recommended to help bring down the fever and help make your goat more comfortable.
If the temperature is normal, then monitor your goat for urination and defecation. Does it seem like he is standing with his hind legs parked out behind him, with his tail in the air and grunting? Is he producing small amounts of urine from his prepuce/penis? If this is the case, this is an EMERGENCY! Your goat has a partial obstruction in his bladder/urethra. He will need veterinarian care immediately. Unfortunately there is nothing you can do for this. Your vet will need to try to pass a catheter into his bladder to try and clear the obstruction.
If he is urinating normally, then I recommend having your goat checked up by a veterinarian. Unfortunately, his symptoms can represent quite a few things. The three things I have listed are the most common affecting a neutered male goat with the symptoms you describe.