Confused please help

Tasha
I'm 27 years old. I have a 2 year old daughter now but this never happens. My period ended a week ago but it was very light but I noticed spotting 2 days ago and now I'm having bad lower pelvic pain and back aches. I have had sex with my fiance before and after my period. Is it a chance I could be pregnant or am I'm just being paranoid? Please help.