Pain in the lower back and buttocks is usually Pelvic Girdle pain so it sounds like you might be getting that. I've either had that or sciatica (I've had sciatica when not pregnant and it feels much the same so I'm not sure which it is).

Pain in the pubic region can be Symphysis Pubis Dysfunction or SPD (thank god for google). I think I might've started to get this last night. It started whilst lying in bed when I tried to shift position - particulary while rolling from side to side - mine's mostly on the left, although my buttock pain I've been getting is confined to the right side. Google it and see if that's what it is. My pain sounds very like it. I'm hoping not though cos it sounds like it generally hangs around for the entire pregnancy. Didn't get a lot of sleep last night.