93 accord ex horrible sound at certain rpm

93 accord ex 240k miles on it...recently heard a barely noticable "whistling noise at about 2,100 rpm....than as about 2 weeks went by the noise kept getting worse and worse..now its a rusty noise(not like a moped or scooter) mixed with clicking and some small whistling,and its from anywhere between 1,500 rpm-2,350 rpm. i figured it was the exhaust with a small enough hole to make it sound like whistling and it worsened as time went by..but when i check the exhaust its perfectly intact with no holes...and whats even worse is i know its not the exhaust because it even makes the same noise just not as loud when i hit a speed bump or a small hole in the street..any help at all would be apreciated this is my first and only car...i just want to nurse her back to good health

-belt is almost new
-oil change no more than 500 miles ago\
-filter is secure