I suffer from sciatica occasionally, and had my first big flare-up for years just a few months back. Funnily enough, cycling helped. There was no pain whilst cycling, but it was excruciating standing up straight again afterwards, and I'd have to walk across the car park into work looking like a half-shut knife until I could slowly straighten up.
In the end it was rest, prescription-strength Ibuprofen, paracetamol and heat that chased it away.
It's awful. Even when you're not moving there's the terrible 'toothache in the leg' pain radiating down as far as your ankles.
Hope your Mum recovers soon, Arch.