unnecessary FIBEROPTIC LARYNGOSCOPY procedure?

[fibur]

I went to see an ENT specialist few weeks ago for a very minor throat pain issue past around 8 weeks. ENT performed FIBEROPTIC LARYNGOSCOPY(FL) without any written consent, precautions, literature, etc., around this procedure. This was my first ever visit to this doctor and there was no special preparations advised prior to the appointment like fasting, etc.,

According to this website, one should not eat 6-12 hours prior to this FL procedure: https://www.montgomeryent.com/fiberoptic-laryngoscopy-ent-surgeon-cincinnati-wilmington.html
But this ENT just started performing this FL procedure without asking any questions on prior fasting etc.,

2 days after the procedure, I had severe throat pain that I couldn't eat, drink, swallow saliva. Everything hurt so badly I wanted to go visit Emergency. Never felt that pain in my life. Remember, my pain level was almost nil (very mild) before this FL procedure.

I had a second opinion from another ENT who performed throat inspection using Mirror laryngoscopy which is not intrusive as FL but gives similar visibility. He also said FL was unnecessary.

I still have throat pain severe than pre-FL procedure.

Is this a potential medical malpractice from this ENT?
What is my recourse?