Yoga is good for getting baby to move out of an awkward position...child's pose (knees open to give room for bump) is great as it stretches the back and brings baby weight to the front away from nerves etc. Being on all fours might help too. Also try sitting on a gym ball - it ensures we sit on the sitting bones with our back straight. Lounging in a chair with a curved spine will make things worse as will sitting in a standard car for any length of time. Luckily, at 17 weeks there's still plenty of room in there for baby to move around :)
I have pain on the lower right side of my belly the Doctor says the baby is on a nerve. Have her try yoga stretching usually helps with the pain.