Help interpreting chart, second dip after confirmed ovulation

I am ttc so I’m hoping this is an implantation dip. But wondering what other causes it may be? I confirmed ovulation at cd 15 with positive LH test and temp drop. Wondering if there’s other reasons why I had a temp drop on cd22. Usually I stay above my coverline after ovulation. I haven’t been sick or drank alcohol ( my doc said that can alter your bbt). These previously said I ovulated on cd15 but is now inside after I added today’s high temp. Thanks in advance!