Hello BetHar,
I had a similar experience. I fell on my left side as well. I did more damage to my hip and thigh though. At the time you went to the doctor you lower symptoms may not have pronounced themselves yet. You may of hurt more of yourself than you realized. You need to take it easy. I suggest cold and hot compresses to ease the soreness and pain. Chances are your doctor already told you that. Don't put any strain on your hip or lower back or shoulder. You might try soaking in the tub if you have one. I've found that ibuprofin or motrin work well on pain of this type of pain. I don't think you have anything unusual but you need to take it easy for a couple of weeks. I surprised that you could sit down with any pain. A lot of times lower back pain and hip pain can make it difficult to sit.