BBT drop 5DPO

Nicole
 Has anyone had a BBT drop 4-5DPO? Last week I checked my temp at 6am everyday and this week at 4am so I know that might effect charting. But I was at an increase for 4 days and this morning I was 97.1!! Is this an estrogen surge? Or did I not truly ovulate? Would love to hear if someone had a cycle like mine and got a BFP!