I would recommend using tylenol. Your baby weighs 27 pounds, or 12 kilograms (kg) (1 kg = 2.2 pounds). Knowing that you want to give 10 milligrams (mg) for each kg to start, you would give 120 mg per dose. This could be increased to 15 mg/kg per dose, so 180 mg. One should not exceed 5 doses per day, so give one dose every 4-6 hours as needed.
If the tylenol in your possession has a concentration of 80 mg per milliliter (mL), then one would have to give 1.5 mL to equal 120 mg.
Hoping it is all helpful, I wish him a speedy recovery and wish you a nice day.