I think you tried a physio before? I've had severe SPD and have seen a few so can recommend you a good one if you're interested. She's in East Melbourne.

I'm not absolutely sure from what you've described whether you have SPD or not - certainly if you're having problems lifting your legs, then it could be.

Ice can make a HUGE difference - particularly at the end of the day. Get an ice pack and put it wherever's hurry and yes that means between your legs.

My current physio tells me that not many people can tolerate ice on their back so maybe a heat pack instead.

You can also get a support belt. Tubigrips are alright but I found the belt better.

If you go to the physio I saw, they will also get you doing clinical pilates to strengthen your core.

Mine was particularly severe because of a bad birth first time around (don't fall for the line that 'it just goes away' - mine hasn't five years later), so you might want to read up on optimal birth positions - check out the Pelvic Instability Association's website.