I'm so confused

Elizabeth
On today's episode of "What the Heck is my Body Doing", we ask, what the heck is my body doing?
Featuring guest stars:
3 days of spotting
Cycle Day 45
And your host, LH Surge!
Last cycle I ovulated on CD 47, but I had spotting a couple weeks before that for two days. This is day 3 of spotting, and no positive OPK yet, but this mornings test was significantly darker than yesterday's
Anyone care to take a gander at what this could be from?
I took a pregnancy test a few days ago, and it was negative