Hi Raizzy, congratulations on your twins - you must be exhausted!
I haven't been in your position, thankfully, but I have a friend who developed a hip problem after the birth of her daughter. So, she eventually got help from a physiotherapist, but initially, when in bed, she had one of those long 'body' cushions, if she was on her side she slept with the leg of her effected hip resting on the cushion so that it didn't put strain on the hip joint. Her Dr, and then the physio had a good look at the hip joint to make sure there were no physical problems with the joint itself (very important, apparently, as there is the potential to have missed a congenital hip issue that's been there all along - her daughter turned out to have one not diagnosed until 2 1/2). When they knew the joint was fine she was given exercise to improve the movement and strengthen the support muscles. Good luck.
