Can Botox cause a fever several days after having it ?

It is highly unlikely the fever is caused by injection of Botox. I suspect this is a coincidence. Redness, drainage or increasing pain at the injection sites may indicate a rare but serious complication. In the extremely unlikely event you experience these problems, you should seek urgent treatment. 

While flu-like symptoms are a potential side effect of Botox, it is not common.  Your fever is likely from another source and the fact that you recently had Botox is probably a coincidence.  I would see your primary care physician or your injecting physician should it persist.  I wish you well!