Check with your OB first to make sure this is OK.
If you can find the money to spare, this is not only good for you mentally, but also physically.
Call the day spas in your area. Ask if they do prenatal massage. You will feel wonderful when you are all done. it relieves muscle aches, tension and will work on the back pain. Some research is looking into its effects on baby. There are many OBs who believe prenatal massage can help calm baby down, have a positive effect on him/her after he/she is born, and possibly make labor easier because the muscles are not as tense and tired.
I had one at 8 1/2 mos and felt great. My back was fine until after labor, and thats impressive considering how many back problems I have. I only had to push for about 45 minutes and I rested for at least 20 of it.
Check it out. you'll find that some spas are reasonable, especially with prenatal massages. They usually last for an hour and are tailored to the needs of a pregnant woman's body.