Sciatica is complex and encompasses multiple causes and symptoms. Mine rarely affects my back, but is murder on my right hip and leg.

In any case, the first and (hopefully) best defense is exercise to maintain flexibility and movement.

However, since this is a bike forum, some questions.

Do you have a history of Sciatica and this is just a flame up?
Do how long have you been riding, and what, if anything, is changed over the last 6 months?

These are important because if you have no history of sciatica, and changed anything since June, there's a possibility that the two are linked. For example, a saddle slightly too high can cause your hips to rock and lead to sciatica symptoms. On the flip side, long saddle time in a position that you're not really used to can also cause issues.

So, think about the questions, and as you recover, think about whether the sciatica and cycling may be related and how. Hopefully, with some detective work, you'll find an underlying issue, and by resolving it, prevent future issues.