For pelvic pains, for short-term relief, you can try panadol but that didn't work for me. I used a hot compress on the area that hurt, I find that is minimal relief too. In the end, I was very conscious of my posture and the way I do things. E.g. when sleeping, I would turn around in bed very slowly. If i'm on my side, I would turn slowly onto my back first, then pushing my knees up (by walking them up the bed), I would use the weight of the other leg to go down onto the other side. Not sure if I'm describing properly. But I find that for me, coz my left hurts, it's more comfortable to sleep on my right. And yes, no more breaststroke if swimming. When getting in and out of car, swing both legs in instead of putting one leg in/out first. Be conscious of the way you walk, I realised that I am learning to control my pelvic movement. That way, it won't hurt so much, and walk slowly!
I got a Britax Royale carseat. Retail price is $499 but Robinsons had storewide 15% previously. That one can use from birth to toddler, so quite worth it IMO.
I'm also feeling a lot of pressure in my pelvic area now. Don't know when baby wants to come out and see the world, but i'm only 33 weeks. So still too early!