Did you have a fever with this swelling and redness?
The history sounds more like "diffuse local reaction to insect sting" than cellulitis to me. This is a local toxic effect of insect stings, causes considerable swelling and redness of the limb, but not associated with fever. Steroids and antibiotics are not indicated for treatment, as a matter of fact, nothing much helps except elevation of the extremity. I see this all the time here in sunny 'ol Fla; that being said, I can't fault the docs decision to put you on that treatment regimen, as differentiating the two can be difficult, and delaying treatment for an aggressive cellulitis of the arm is problematic. If one has the choice, close follow-up, with the patient taking his/her temp. 4x/day and immediate return for treatment as needed is how I handle these things - *but not over the Internet*!