What can cause neck pain and a sudden incidence of moderate to severe head pressure with a buzzing sensation in the head lasting only 5-10 seconds?

Several things. Your symptoms maybe coming from a couple things. Sinus infections and middle/inner ear conditions can cause head pressure, headaches, even balance problems. Your neck pain could be separate or compensatory to maintaining your upright stance (for balance). I would rec that you start with an appt with your pcp for an exam. If the diagnosis is not obvious, referral to an ENT is next.
Neck problem. I would be suspicious for neck problem. Disc, arthritids or vascular obstruction. Do symptoms change with head movement?