Alot of women get back ache in late pregnancy just due to all that extra weight out front! Make sure up don't slouch as that will make it worse other than that there isn't really much else to do about it. I got leg cramps during my pregnancy - the midwife said it had something to do with lack of calcium I think (god it seems so long ago!) have a chat to your doctor/midwife they should be able to suggest something that may help.
Thanks im just resting and keeping my feet up at the moment like my mum is advising me. It might be too late by the time I can get in touch with my midwife as she is on holiday for two weeks and its a bit far for me to travel to the doctors especially in this heat. Fingers crossed it'll get better with alot of rest