What is the best mattress for someone with sore shoulders? I weigh 105 lbs and usually sleep on my stomach. I wake up during the night with pain in my hands and numb fingers. I think this is due to carpel tunnel, but am curious as to the effect the proper mattress may have on the problems. I have always slept on a very firm mattress, but am now buying a new one. Is memory foam worth the investment? Is a plush mattress better for back and shoulder pain?Thank you.