My pain is associated with movement. Is that what yours was when you were miscarrying?
I don't want to alarm you... but when I was 15 weeks I had back aches and everyone told me it was part of pregnancy. No cramps, just minor backaches. I had an appt. with my OB already scheduled, so when I went to see her, I found out that I was miscarrying. Not saying that is the cause of your backache, but I would rather you be safe than sorry and give your OB a call. If you describe it to her, she will better be able to determine if you need to be seen or if it is "normal".
I have horrible back pain all the time, i lay on a heating pad every night before i go to sleep... and i also use a little pillow for more back support when im sitting at my desk at work. it helps a little.