Faint BFP then BFN

Hi everyone, I took this test yesterday morning. I am 3 days late today. This morning at 2am I took another test but it was negative. Not sure what to think. I have lower back aches, and occasional nausea. What do you guys think? I usually have a 28day cycle, I do not temp or anything have not really tried for long as my husband is out of the country on business travel. Thank you