WTH BBT drip then rise?

Ak
Yesterday morning I took my temp it was 98.4 yesterday this morning was 98.1 then I take it again 15 mins later and it's 98.8
Implantation dip?? 
I track my temp during the day to see how much my physical actively affects my temp and it barely moves even with movement and for me to get up go to bathroom lay down for couple then retake it that's a big spike for my body so maybe Implantation dip??