My Muffin will wheeze when she's scared, like when you pick her up. Might it be this? What is the medicine? Are you sure it's a sickness and not just fear? If you think he's sick, you really need to go to the vet. 3 is not very old, and if it is an upper respiratory infection, you need to make sure you treat it with the right antibiotic. Rabbits are very sensitive to antibiotic use due to their complex intestinal "good" bacteria, and many upper respiratory infections in rabbits are caused by bacteria that are resistant to some antibiotics. The vet will do a culture of the bacteria and determine which antibiotics will kill the bacteria. If you cannot afford to take your bunnies to the vet, consider CareCredit, which is like a credit card for veterinary care that you can pay off gradually. Some vets will also do installation payments. Some shelters can also help you get lower cost veterinary care. I hope it's just him being afraid of being picked up, but please consider that you have a responsibility to provide veterinary care for your animals.