Bfp then bfn symptoms getting stronger

On Saturday I got a bfp on frer. Faint bc I was still early but it was there. Tested again yesterday and it was complete bfn with FMU. wtf. I assumed I was having a chemical but my symptoms are getting stronger and stronger. Breasts are SO sore to the touch and my teeth are killing me(always a symptom for me) I’m extremely exhausted and taking naps in the afternoon. AF is due in 2 days. I will test one more time tomorrow with FMU but for anyone who’s had a chemical, did your symptoms fade as soon as you got a bfn? Or did they keep getting stronger?