I know that this time is physically hard on you and your body, but try to enjoy the last few weeks, and make sure you catch up on as much rest as possible, taking a nice long warm bath or shower can work wonders, or if you can afford it why not treat yourself to a pregnancy massage, now that is a treat :)
Google free yoga classes and pregnancy excerises. Plevic tilts help with back pain.
aww i know the feeling... im 33weeks and tired to..not as far as you... but i looked up stretches you can do on you knees to help your back at night.. its like a belly down then back arched.. i really cant explain but it has helped me in my last three pregnancies...