Opinion needed on positive result

Hi ladies, I need help. Period is expected in 3 days. I woke up this morning and ate cereal and went to do my nails. In the salon I realized how much my lower back was hurting. I never get lower back pain around my period and thought that was strange. Went home and took a test and initially only one line appeared but then quickly the second line appeared and got stronger.

They say testing with the first morning tribe is most accurate so I’m having doubts. Do you think eating cereal (and no other food or drink) could be giving me a false positive?

What have been your experiences? Thank you for your guidance.