I was slapped yesterday in the evening and I've since had an mostly overwhelming ringing in my left ear. What is going on?
How soon should I see a doctor versus trying to ride out the issue, meaning if the issue persists, when should I go in for help?
You should go to the doctor as soon as possible. You have an acoustic trauma and you may have damaged your eardrum.
First you should ask him to see if there's any physical damage to your eardrum.
Then you should ask for an audiogram (extended up to 16000 hz would be ideal) + OAE + DPOAE.
Don't do acoustic reflex test it may aggravate your condition.
Then you should ask him to write a prescription for steroids (Prednisolone or Dexamethasone). Ask him about intratympanic steroid injections (they have more potential than systemic steroids).
If your doctor refuses to give you steroids tell him that you have an acute acoustic trauma. Lie if you have to. Tell him that you've been exposed to a gunshot or a fire alarm. If a doctor dismisses you just find another one. Be persistent and don't get discouraged.
You should take at least 90 mg of Prednisolone or 12 mg of Dexamethasone for 5 days and then reduce the dosage.
If you can get admitted to the hospital you should discuss with doctors higher doses of steroids. Typically in cases of acoustic trauma the dose is 250 mg of Prednisolone for 3-4 days and then taper. In case of Dexamethasone it's 40-40-40-10-10-10 mg. These are extremely high dosages and should be taken under doctor's supervision.
But in your case the risk might be worth it.
Steroids are most effective in first 24 hours and first 7 days. Don't waste a second.
You should start HBOT immediately. At least 1.3 atm for 60 minutes 10-20 days. If you can find HBOT units that go up to 2.5 atm that's even better. Betahistine (48 mg split in 2 doses daily) + Ginkgo Biloba (120 mg + daily) will give you better results with HBOT. Trimetazidine (70 mg split in 2 doses daily) might be beneficial too.
Regarding supplements you should take Magnesium citrate + B12 shots + NAC (600 mg+).
And don't use headphones (even at low volume), because they may aggravate your condition dramatically.
Good luck.