Two days is still early days for treatment but you should start seeing some improvement in the next day or so, I would say to give it the weekend and if there is no improvement in Jinx’s condition you should return to your Veterinarian on Monday for another examination. Improvement in an animal's condition, especially with antibiotics, can be delayed in most cases so unless your Veterinarian said specifically ‘you’ll see improvement over the next 24 hours’ or something similar you should give it three or four days at least. Regards Dr Callum Turner DVM
You should keep an eye on the kitten for now and ensure that he remains hydrated; rapid breathing may be attributable to numerous causes but shouldn’t be an issue unless he is in distress. See how he is over the next day or two, but if you don’t see any improvement you should visit your Veterinarian for another examination. Regards Dr Callum Turner DVM
There are various different causes for rapid breathing which may include infections, pain, heart disorders, dehydration among other causes; a cat’s respiration should be below 30 breaths per minute when at rest but if it is significantly above this rate at rest I would suggest visiting your Veterinarian for an examination to determine a cause. Regards Dr Callum Turner DVM
Rapid breathing (tachypnea) is a respiratory disorder characterised by abnormal breathing that is rapid and shallow. It is caused by a reduced level of oxygen, mechanical disorders (where the lungs aren’t able to expand as they should, usually due to a build-up of fluid in or around the lungs), and physiological disorders in which the cat’s respiratory centre in the brain is over stimulated.