brown bleeding for a week, and early

Im 21 years old and already have 2 children 3 and 1. I havent been using brith control or condoms, and me and my husband have been married for a year together for 5years, havnt been trying for another but not pretecting. my period isnt due for a week from today, ive been having a weird brown bleeding, its been fairly light, a little heavyer not too heavy at one point and ive been having it a week. It started just over a week and a half after my last period. 2 days ago i went to the doctors and the said a pregnancy test was negitive but there was a slight infection(i get bladder infections alot) but i know a pregnancy test wouldnt be postive this early anyway. Last night i had sex and hit was hurting and felt like hit was hitting my pelvic bone, the only other time i felt like that before in sex was pregnant with my 1st. Could this be me pregnant and my implantaion bleeding is just diffrebt from most. or should i just wait it out for a week and a bit till my period comes? (bleeding has stopped since 2 days ago, but i still get a slight spot here and there.