A number of not important flutters can happen and are okay. My experience with afib is that, your pulse will never hold low as 76-80, it will be going up and down, never staying low until you are in Normal Sinus Rhythm. In order to get back to normal rhythm, one possibility is the electric shock, another possibility is having a drip to help it along and simply waiting. Now I don't go to the hospital, and afib leaves in 7-10 hours, same as it did in the hospital (I rest the whole time). I know I am in afib because my pulse is almost impossible to take, it feels like a grand flutter. If I use the home blood pressure device, it reads as a high pulse, perhaps 138-145-175.
Your possible 3 day hospital stay was if you were being started in Sotalol (or Dofetilide.) They both require the hospital stay to see if they give you bad reactions. Mine didn't and I have taken Dofetilide for 4 years. Curious that no one has given you an EKG, regular practice for afib patients, in or out of afib at that time.
One trigger for my afib is more hard work than expected. If you lost so much weight, you must have a lot of ability to work hard, hope you're also giving yourself time to rest. Good luck!