Re: pain/swelling relief
Sounds like military care.
Retired Army doc/flight surgeon here. Still in practice.
Mono is caused by an infection from one of two viruses, EBV or CMV. EBV being the most common it causes about 75% of all infectious mono and you don't have to kiss someone to get it. Once gotten, it stays with you for life. Generally. The virus incorporates into the nuclear DNA of liver cells and may come out from time to time to make you just a little sick, a little achy, "flush" then go away. You will be shedding the virus for weeks to months (some data show people "sharing" mono for upwards of 18 months, it varies).
There's nothing specific you can do or take to hasten your recovery. Sleep a lot. Watch netflix. No chick flicks.
Tylenol (acetaminophen/paracetamol) OR Motrin/Advil (ibuprofen) can help with fever and achiness. Look for throat lozenges with "slippery elm" (it's an herbal thing, they should have this in Japan) or anything with benzocaine for gargling OR chloraseptic spray. Chloraseptic used to be formulary in most hospitals until the era of Clintonian downsizings in the 1990s, but I seem to recall it was available locally around 2006.
Fluids. Force yourself to drink fluids. Like we told our guys in the sandbox, "pee clear." And no, IV hydration isn't ideal, plus no one really wants you spewing virus in their emergency room.
Echinacea ONLY works to prevent viral illnesses; taking too much too often it's associated with some blood cancers.
I have, in some rare instances, prescribed steroids (60 - 100 mg of prednisone daily after a 125mg injection) for severe cases. If your tonsils are close to meeting in the middle, you're choking, drooling, CAN'T swallow, get your ass back to the ER and tell the to DO SOMETHING.
Mono isn't always a mild illness. In your copious free time, google "infectious mononucleosis AND fulminant hepatitis." Seen it. Isn't pretty. If your urine starts turning brown or your eyes then skin turn yellow, GET TO AN ER.
I'm sure your docs have taken the time to explain all this to you.
Be well. And thanks for your service.