Oh lol, that's okay! I've got little tanks all over as well and I totally forget they are there as well since I focus on the bigger tanks! And yes, a 1 gallon is perfect since you can dose the salt and/or medications usually easier. So as I said, start with the Epsom Salts and hope that it is just a fluid build up. If she/he needs meds, depending on the med type we can use Epsom Salt in conjunction with the medication for maximum efficiency IF it is necessary. If the medication is doing a great job battling infection, then there is no need to add Epsom Salts to just increase stress levels of the fish.
While fish are sick you want to keep their stress levels down or at least try to. I suggest at night covering the QT tank with a towel or blanket, this helps keep the fish calmer and a calmer, happier fish will have a better chance at fighting off infection because the immune system isn't so compromised by stress. That make sense?
Can you still get pictures? Pictures will help you determine if the swelling has increased or decreased through time as well, I always take pics when my fish are sick so that I can compare them and see what is helping and what might not be helping :) And to show others to get their opinions as well, two minds are better than one ^_^