I'm 31 weeks with my 2nd baby, and have been on crutches now for the last 9 weeks - and I now use a wheelchair when I go any distance - I am having weekly hydro sessions at the hospital, and the NHS trust I come under has a complete support package (including home care) for women suffering with spd (or pgp - pelvic girdle pain as they've started to call it).
However, I only got at the help because I got bolshy - I asked for a referral to physio at 16 weeks, as the spd had returned with a vengeance very early on, to be told that there was a long waiting list ... so I hung on (for 5 weeks), until I heard a colleague (also pg) talking about the fact that her referral had taken all of 10 days to come through!
I have to admit to taking matters into my own hands - I phoned the physios at the hospital, to ask about the status of my referral - only to be told that no referral had been made ... was a tad as you can imagine!
Anyway, this rambling tale has a moral (eventually) - if it is getting to the stage of limiting your mobility (I ended up signed off work because of mine!), then you need to see a physio ... I'd give them a ring (ask for the women's health physios at the hospital), and place your face.
Good luck ... it doesn't last forever!