I have sheep and not goats, but the first thing I would do is check his temperature!!!! Do you have antibiotics on hand should you need to treat him for infection?
Temperature is a very good first indicator of a serious problem! Hoping he will be okay and that goat owners will come on here and give you good advice!!!
Check his temperature.
Did you just bring them home?
"Shipping fever" is common when bringing a goat to a new home. Not serious, but pneumonia can set in fast so you need to watch closely.
Do you have antibiotics? LA 200
Get a temp and call the vet.
The stress of leaving his home and coming to yours can be a very dangerous time for a young goat.
He is likely to succumb to shipping fever which is type of lung infection aka pneumonia. This requires antibiotic treatment. You will need the right med and correct dosage.
Your goat may also wind up with a coccidia bloom due to stress. This is a killer in young goats.
Personally, if I know a young goat is stressed, I do a prevention round of cocci treatment. I would rather treat a goat that is still eating and drinking versus try to keep a real sick one hydrated.
In addition to the above since you will wind up with using a vet you may as well get a fecal done. This way you will know exactly what the little fella has and what you need to treat it with. Guessing only wastes time, and money and possibly the long term health of your goat.