FJ get thee to a chiropractor! One that specialises in working with PG women. The earlier the better as the muscles then get overly tense and it can take longer for them to recover once you've been re-aligned.

In the meantime be really careful with what you are doing about the house. If your pelvis is out of alignment and you carry on lifting washing baskets and vacuuming you can make it more painful for yourself.

Being your fourth bub things are getting quite soft in the ligament department. I had it with my previous one and it was bad so I'm acting like Lady Muck ATM

Tips for going about your every day stuff are:
Don't sit with your legs crossed our tucked up under your bum. Keep them elevated if you can or at least even.
Sleep with a pillow between your knees.
Put your bum on the seat of the car first then swing your legs around together (opposite for getting out of the car swing both legs out first then stand up).
When you get up off the floor don't kneel on one knee, crawl over to the couch or other bit of furniture and stand up using both legs evenly (can take a bit of getting used to that one).
Go for a gentle walk every day.