My 5 year old , 15-17lb mixed breed tom cat.Appears to have a sting or small insect bite on his front left arm, between his shoulder and elbow. It is slightly swollen and he does limp a little when he walks, but I can tell it is bothering him.I was wondering what OTC I could give him for pain and swelling? and what should I use to put over the spot? (its very small spot like sting bite I almost could not see it and it feels like a small bump,no blood)