Was it a period? Could I be...?

I posted this somewhere else and realize it was probably in the wrong category. So here it goes:

I have really regular periods (30 day cycle every month) that last 7 days each time. My June period came right on time (June 3rd) and was completely normal, but my July period came 4 days early (June 29th) and was only about 4 days long. My flow was definitely heavier than any kind of spotting and was accompanied by the normal, terrible cramps, but it tapered off pretty quickly.

I started having mild AF cramps in my belly (which is where I usually get AF cramps) and my lower back (totally new for me) 5 days ago. This is my 5th day of cramping, and I'm wondering what could be going on. It's too early to ovulate, and ovulation cramps usually only last a few hours for me anyway. Since these new, out-of-place cramps have started, I've also experienced a couple of headaches, pretty crazy thirst, and sour/rotten/empty stomach that is sometimes followed by nausea. I've been resting/lying down a lot lately, but have had trouble falling asleep due to the yucky tummy feeling.

I took an HPT July 5th just on a hunch and July 10th after having a couple of days of cramping. The first test was a definite BFN, but the second one was ambiguous. There was/is a faint line (toward the end of the max wait time), but I feel like it's probably an evap line.

If I am pregnant, I would guess that I am 5w 1d and that my last "period" was implantation bleeding or my body going through the motions of AF (as I've heard some women do). Has anyone else experienced this and gotten a BFP? I am having a date night with DH tomorrow and plan on testing with FMU in the morning so that, if I do get a BFP, I can tell him after a great date night.