This is completely incorrect. It is much more likely to overdo nicotine through smoking than vaping. vaping is far less efficient in getting nicotine into your system that smoking is.
Based on the thousands of people who vape higher nicotine levels than the OP does without any of these symptoms, it statistically seems more likely that this could be a "flavoring" issue or possiblely an issue that has nothing to do with vaping at all. It could even have to do with stopping smoking and some chemical that the OP is not getting any longer. As someone else suggested, I would schedule a doctor's visit.
I'm not so sure about that. Being able to vape all day without becoming sick due to excessive chemicals, tar, smoke, etc. makes it is a lot easier to take in more of nicotine with less warning signs. Sure, you don't get as much nicotine as a cigarette gives you, but you're more likely to get sick from smoking cigarettes before you even OD on nicotine in the first place, or at the very least be well aware of the situation.
If you're saying 1 puff of a cigarette is giving you more nicotine than 1 puff of a PV, then hell yes. But tell me this, can you vape longer than you'd be able to smoke cigarettes? Couple that with the fact that nicotine induced via vaping takes longer to hit you, you may well vape away for hours and all of sudden realize you've overdone it.
But back to the original question - now that I recall, when I was on 18mg this was in the first month of quitting smoking, and when my ear ringing had mainly occurred . Like others have said, just quitting smoking can be the cause of ear ringing.
And going to see a medical professional is never a bad thing.