Prenatal vitamin and spotting?

So I’ve been spotting throughout this cycle and weird stuff has just been going on with my AF in general.

I thought I had implementation bleeding a week or so ago, I’m 4 days late, and having spotting that’s almost stopped, again!! Also had weirdly specific cramping on my right side ONLY.

I thought I was miscarrying or at risk for an ectopic pregnancy so I made an emergency appointment with my doctor.

Their test (urine only) came back negative. She basically said bodies are weird and I’m probably just getting ready to start my period.

The only thing I can think of that’s different is I started taking a prenatal vitamin.

Every website says they don’t cause spotting but I’m seeing A LOT OF message-board posts with women asking the same thing and saying they’re having similar experiences to mine.

Just wondering if anyone else had fairly regular, predictable cycles, took a pre-natal (before pregnancy) then had their bodies go all out of whack?