Fractured mandible treated with 1 plate on my right body and 2 on my left angle 3 weeks ago, swelling keeps coming back is it ok? what to expect?

See oral surgeon: At 3 weeks, persistent swelling is unusual, suggesting an infection. See your oral surgeon to make sure everything is ok.

Depends: If you said you still had swelling at 3 weeks, I wouldn't say that was abnormal. Some patients have swelling that may persist up to 6 weeks, although most have resolved in the first 2-3 weeks. What makes me concerned is that you said the swelling went away and came back. This could be a sign of infection of the plates or malposition. See your surgeon ASAP