Annoying brown spotting!!

Melis • •SAHM. •Lover of makeup and books. •Pinterest addict. •Centrist. •Tarot and spirituality.•
Okay, so my periods have been all sorts of wonky since this past May. I got it way late in the month and it only lasted half a day with a day of spotting. Then I missed AF altogether then the of June. Took four PT and all came out negative. Got AF in July for 9 days. Got AF this month for about 8 days. Now, this is day three of brown spotting. I had some brown spotting last month as well but figured it could be some old blood from missing my June period.
What could this possibly be?!
Thank you in advance!