I took my dog I just got as a gift into the vet today. She was from a shelter she is a chihuahua they think shes about 2 yrs old. I took her in because of a cough, they said she had an upper respiratory infection. they prescribed her zithromax 40mg/ml 1ml every 12 hours liquid form, and torbutrol 5mg, half a pill every 8-12 hours as aneeded for cough. i gave her half the pill and 1ml upon arriving home and she seems to be VERY lethargic, not really doing anything but sleeping. Hot...is this normal?