Talk to Pediatrician on Eye Ball Seems Dislocated Sometimes

My 10 month old son fell off bed a few weeks ago. We noticed that his eye ball seems dislocated sometimes since then. Got him checked from a child specialist, he says that you observed it late it could to be there all along. But that's not the case.

Basically my son is one of the 10mo old twins, delivered 4 weeks earlier. So the doc thinks that it may be due to weakness/ oxygen deficiency issue right after birth (which I kept both under nursery as long as the doctors suggested) and prescribed so. But the dislocation, i think, is getting more visible. Who should I take him to?