Lower Back pain :-(

I missed my period yesterday but I took a test and it was negative. I've been having awful lower back pains for bout 5 days now. Very tired. And smoking makes me feel sick... which is odd for me cuz I'm a daily smoker (unfortunately). Could this possibly be a good sign? Me n mine have been ttc for about 4 months now with no luck at all. I don't know if I shud wait longer to test? I got no sign of a positive... may be all in my head. Just a lil frustrated so had to vent :-(