It sounds like a respiratory infection to me. Being stuck at home sucks, but usually vets still work on emergency cases, so if it really seems awful it might be worth to arrange something.

The most common treatment I've seen is this one shown here: https://ball-pythons.net/forums/show...-from-Home-DIY. Amazon might be able to ship you both the F10 disinfectant and mister.

If NOT... do you have a couple of plastic bins? For this you need a small plastic bin for your snake, and another plastic bin about twice as big. Drill several air holes into both bins. You'll want a decent amount on the smaller one, and a few less on the larger. Place your snake in the small bin. Then boil up a pot of water water, and add half a tea spoon of vicks vaporub. After you add in vicks, leave the top covered until you place it in the large plastic bin.
When you place in your pot of boiling vicks water, you can put it either on top of the smaller bin, or next to it depending on size. Use a hot pad, so you're not melting any plastic. Then remove the pot's lid, and close the lid of the larger bin. That'll let the vicks mist in there a bit. Check on the snake after five minutes, then put the lid back on, and take it out after another five minutes (total 10 minutes). If you can do this once a day for a several days, you'll see improvements.

Also, not knowing what kind of enclosure you have it in, but I'd pay attention to making sure the humidity and heat are high enough in the enclosure. I'm also not sure what you use for substrate, but it might be worth switching to paper towels for a little bit, just in case. It's easier and quicker to clean, and better at showing any usual "discharge".