weak motor

i got about 2 thousand miles on my motor and when i bought a year ago it ran ok and it gradually got worse i always change oil at 2000 miles cause i am paranoid about it and just did tranny. there is a small knock in the motor and i am lost

that knock in the motor might be a rod fixing to go. my advice is to get it checked out. if you dont you could throw a rod through the side of the motor, and their hard to get to and replace.