Vehicle Fraud by a dealer (Nissan Altima 2017)

Purchased Nissan Altima 2017 3-4 weeks ago.
I suspect the dealer sold me an accident vehicle and did not mention it as an
accident vehicle while purchasing it .The first week was good. Then the
actual issue arises, a suspicious fluttering noise while accelerating the  car
from rear, AC makes noise. huge noise(Engine) while trying to accelarate  
from stop. And the dealer seems have  repaired the rear of the vehicle from
a local mechanic to avoid a report on Carfax report as it seems like the
bumper twin exhaust and the tail light are not in proper shape and paint
which i haven't noticed while purchasing.