Glaxo Smith Klyne fined $4.2 BILL for killing kids., page-28

You had Atrial Fibrillation (AF) that spontaneously reverted. Nothing more. Happens all the time. Some people do exactly what you do for the same reason (over-runs the other pacemakers and then allows the Sino-Atrial node to resume pacemaking duties). No miracle there at all, just well observed self-initiated treatment. It is not a cure BTW, the underlying issue is still there, a second or third irritable area in your Atria that can and will take over the rhythm from time to time making the atria wobble like jelly, rather than rhythmically contract. Usually benign, but can cause issues with low BP and is related to the formation of blood clots in the atria, clots then breaking off, going through the ventricle/root of the aorta then getting into coronary arteries = heart attack, or to the brain = stroke. You should talk to your GP about having a 12 lead ECG done, and possibly low dose aspirin, and to get an accurate diagnosis. You could ignore it (and my honest advice as an ED RN) and take your chances, but I sincerely hope you do take the time out for a 20 min checkup with a GP. Print this out if needed and show to your GP.
They still make aspirin, and that has been around since whenever. They are still researching its uses. Plant extracts, including willow bark and spiraea, of which salicylic acid was the active constituent, had been known to help alleviate headaches, pains, and fevers since antiquity. It is not true that if a substance is derived from natural sources Big Pharma loses interest, indeed some new drugs have to be derived from natural sources (cone shell toxin for some powerful analgesics for example).