how to solve the integro-diffenertial equation?

i want to get the solution of this ode

b33 = 20*(2.52077405993092./(46.4663900509659 + (omega-1).^2 - ...
11.8316929905336.*(omega-1)));

and i use `fit` method to get the `k33`

 k33= 
  20*(-1.01880661301011*...
 sin(-12.2868520317448*t)/(12.3729623105373*t + ...
    31.6231386532942*t^2));

but it is of `fit` method and you can int `b33` to get `k33`,but finally how to solve this ode?