I don't recommend 'shotgun' cold meds like suggested. I like to know what I'm taking.
NYQUIL INGREDIENTS
Active Ingredients (in each LiquiCap™) (Purpose)
Acetaminophen 325 mg (Pain reliever/fever reducer)
Dextromethorphan HBr 15 mg (Cough suppressant)
Doxylamine succinate 6.25 mg (Antihistamine)
DAYQUIL INGREDIENTS
Active Ingredients (in each LiquiCap™) (Purpose)
Acetaminophen 325 mg (Pain reliever/fever reducer)
Dextromethorphan HBr 10 mg (Cough suppressant)
Phenylephrine HCl 5 mg (Nasal decongestant)
As you can see it's just regular stuff you can buy off the shelf for yourself. Tylenol for pain, Dextromethorpan for cough (lousy cough suppression, almost worthless), Doxylamine being an antihistamine 'may' help with cold symptoms (more likely not) but the main (side) effect is drowsiness. Cheap Benadryl is a better antihistamine.
Dayquil just adds Phenylepherine, a poor decongestant since Pseuodfed can't be used in these kinds of med mixes anymore (idiots make crack from it). Doubt Nyquil would help at all, except maybe for pain, and Dayquil would be of questionable/minimal benefit.
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You could well have a middle ear infection. Often they will clear themselves and antibiotics are no longer suggested at the first hint of this problem due to the serious overuse of antibiotics for stuff like this.
So, get yourself some Pseudofed, take it immediately and hope it opens things up enough to drain. Personally I would add Afrin nasal spray, AND get a Neilmed sinus rinse kit and start using that. Sure, take some painkiller too.
If you are desperate, go see a Doc now and probably get put on antibiotics. I'd still do the other stuff in addition, won't hurt, probably help. You might want to discuss a short course of steroids
ONCE THE EAR HAS CLEARED, to reduce the inflammation if you hope to dive. You don't want to take steroids if you do have an infection.