Will there be backache as early pregnancy symptom?

well am not really sure if it is but my boyfriend and i had unprotocted sex when i was on my period and the next day i started to bleed harder but then later that day it was a lite pink then it stopped all together well i still have to wait to take a test but i have been getting alot of backaches i still have a nother 10 days to take a test but i have been loseing weight like crazy i went from a 130lbs to 125 in the last four days i really don't feel like eating i have a bloating feeling like am going to start but i should not start for a nother 3 weeks so am really not sure if am pregnant or not but ive had children befour and i have the same thing happen to me when i was pregnant with my second child so it could be