Mine appeared at 6 weeks and went at around 12 weeks - I remember at one stage thinking 'I've felt sick all day and night every day for a whole month now... it's never going to end!', and then end it did.  Looking back I don't remember it being as miserable as it felt at the time - I think it's nature's way of tricking me into having more kids!!!

I kept crackers and dried fruit by the bed, and ate a little something before getting up, but also if I woke in the night feeling rotten I'd have a few dried apricots, which made getting up a few hours later a bit easier.  My midwife recommended chippies - and they were magic!  Oh - and the MS is definintly worse when you're tired so rest up when you need to.