If he has worms, garlic won't fix that... Safeguard 10% goat dewormer is your best bet, liquid or paste... weigh him and the dosage is 0.23cc/mL per pound once a day for 5 days in a row...
I highly recommend Safeguard, it saved my flock of Calls from a severe worm infestation...
I highly recommend Safeguard, it saved my flock of Calls from a severe worm infestation...