Is this an implantation dip?

Hi all. I have a very very regular period/ovulation monthly. Cycles are generally 29 days long with a 13-14 day luteal phase. I’ve never had a tremendous dip like this (on 9dpo) in my bbt since I’ve been charting which has been a long time. I have 3 kids that I never tracked nor tried for. My boobs are very sore and have been for about 3 days now which is also a normal pms sign for me. Normally once I dip in temp it stays low and I get a period the following day but this time it spiked high the following days?