Thank you for your query.
1. Yes, the most likely cause for your dizziness
seems to be your sinusitis
2. An important part of the balance system, the labyrinth and semicircular canals are a part of the inner ear
and hence toxins from the catarrh and sinusitis may cause dizziness.
3. Sinusitis itself may cause light headedness. If you have unsteadiness, it may be due to sinusitis alone. Ear ploblems tend to cause true rotatory vertigo
rather than just unsteadiness.
4. You should consult an ENT Specialist
and preferably a Neurolotogist since you have already banged your head 5 days ago.
5. The first step will be to locate the cause of the dizziness. A plain Sinus CT Scan, Ear Pure Tone Audiograms (PTA)and Tympanogram (Impedance Audiogram or I/A) together with tests for balance should be performed.
6.Ask your physician to start with treatment for sinusitis and ear catarrh including anti-allergic decongestants, steam inhalation and anti-dizziness drugs if necessary.