Could 2 consecutive doses of prednisone (for poison ivy - got it twice) and having a fever from flu cause sperm count to be lower?

Possible: It is possible that a febrile illness could temporarily reduce sperm count in a male. It is unlikely that prednisone in short course therapy would do so

Unusual: It is possible but unusual to have low sperm count with only 2 doses of prednisone. High doses and prolonged use is more frequently associated with this side effect. Fever can also affect the sperm count but both things the use of steroids and fever should improve quickly and the sperm count will also improve.

Not so simple: Maybe fever or prednisone will reduce sperm count a little. But prednisone is also used to enhance fertility in case of anti-sperm antibodies. For treatment of ivy allergy, topical therapy with potent creams is preferred. If oral prednisone is needed, 2 or 3 doses, never 2 days in a row, entire dose in AM, is most effective.