I’m a plastic surgeon with extensive experience dealing with facial and orbital fractures from Tan Tock Seng Hospital previously. I am currently in private practice.
The corrective surgery you had for the orbital floor fracture did not adequately correct the floor defect. In addition, the corrective implant is too thick, resulting in impingement of the Inferior rectus muscle. This causes your diplopia, nausea, tinnitus and giddiness. It is a typical occulo-tympanic reflex. In addition, from the photos, you have obvious right enophthalmos/sunken eye.
What you require is a corrective orbital floor surgery, with removal of the previous implant and the use of a properly placed orbital floor mesh. This is a relatively simple surgery which would take 1-1.5hrs under general anaesthesia.
Please feel free to contact my clinic should you require more information.