You should tell the truth, but it's hard once the lie is there. You could say to the Dr. you don't know if you were PG or not. Tell him you took the HPT and it was positive, and then sometime later you got your period. You're not sure if it was an MC, or a false positive test. This could've actually happened, you could've been PG, and had an MC. Probably not, but a lot of people MC very early, not even knowing they were PG. This would not make your medical records false, and be a softer blow to the father. Good luck to you.