Fluctuating BBT I’m very early pregnancy?

Ariel

Feeling a little shocked after getting a positive test yesterday and today. But did notice my BBT was 98.62 yesterday and is now 98.20 today (it was also 98.20 the day before my 98.62 temp) is that normal? I will check again tomorrow morning but I’m wondering if anyone else has experienced this. I’m probably only 4 weeks along and I know the risk of miscarriage is high for several weeks. Thanks all!