Taz - sciatic pain is usually because something is pressing on the spinal column so it originates from the spine and lower back - so there may not actually be anything wrong with your hips. Annie is right, I originally thought it was my hips as the pain was through my hip, buttock and down the side of my leg but it's the inflamed disc, due to the compression between the vertebrae, that is the problem, as it's digging into my spinal column!!!. Having the X ray & MRI was reasuring in one way as the rheumatologist said my hips were great!!! However, the degeneration I have in my spine is not going to get better - I simply have to manage the pain. This is why diagnosis is important and trying physio or the osteopath first for treatment and advice about how to adjust your lifestyle to avoid problems is the best option. You may find that your driving position is creating the problem and they can advice about that??!!! How you walk, sit, lie down etc are all crucial so relearning how your move and sit can really help. As others have said, you may find that an osteopath may be able to manipulate you to relief the pressure. Driving is the worst thing for backs as you are sitting and bouncing, and this will make any pressure on the spinal column worse.
Keep moving though - but gently - and walk as much as you can, taking care with you posture. Dg x