I had spd with my first from 30 weeks, and was basically immobile for the last 5 weeks of the pg ... but there was no real care in place.
I was advised to leave at least 2 years between pg to allow the hormone levels to return to normal, and was then told that I was likely to get a reoccurence earlier and more severely.
DS is now nearly 5, and I'm 34 weeks pg with my 2nd - the spd did come back earlier (started getting the first twinges at 12 weeks) - but as others have said, as I knew what it was I made a fuss and demanded a physio referral - and te trust I'm under has had a sea-change in attitude towards spd. They now have 2 full-time women's health physios, and they offer group help and support, one-on-one appointments, hydro sessions for severe cases, pain clinics and post-natal care.
I am on crutches / using a chair, and have been since 22 weeks, but I feel like I'm better off this time, as I have all the support systems in place to help me through the pg.
Mind you, I still become a whinging mess by about 8pm - and we've decided that this is it in terms of children, as neither I nor my marriage could cope (although part of that is due to the fact that I suffered with hyperemesis until 28 weeks as well!)
Good luck!