Brief Answer:
further evaluation needed...

Detailed Answer:
Hello and Welcome to 'Ask A Doctor' service...
I've gone through your query in details...
I can understand your concerns...

First of all, please note that the back surgery at L3L4 level is unlikely to have any correlation with this new onset spinning and dizziness. However, the possibility of a higher-level involvement i.e. cervical spine related issues can't be ruled out.

Good to know that you don't have blood pressure related issues. However, given your age along with past medical history, if you notice any other symptoms like funny sensation around the lips, cheeks, any problem with vision, any tingling and/or weakness in the arms/shoulders then please don't delay any longer and visit your nearest ER/urgent care for a prompt check-up (as you fall in a high-risk group of stroke, and it should be ruled out immediately)...

As of now, if these are the only concerns, please stay rested, drink a lot of fluids...avoid neck bending for the time being...there could be an inner ear related issue causing this vertigo-like sensation, for which you may take Dimenhydrinate (eg. Dramamine) or Meclizine like medications and observe how you stay afterwards...If despite this, symptoms persist beyond a while, then an ENT check-up may also be required for detailed evaluation...

Let me know if I can assist you further...

Take Care
Kind Regards

---