Cepha symptoms and conditions

Day 4 of taking Cephalexin (500mg) 3 x daily for an abdominal cyst that became infected. Have seen little change in the cyst so far- wondering if it takes longer to work? Side effects: really the only side effect that I can claim is tiredness. Also- in the last 24 hours I developed a very sore throat- no other secondary symptoms like coated tongue or swelling so I am not sure if this is related to the Cepha. I am in Vegas on business s it could be "Vegas Throat" (combination of AC, low humidity and cigarette smoke in casinos) or the start of a cold. I will see in the next couple of days when I get back home where the humidity is 60%.