You could post notices in vet offices, also some grocery stores have bulletin boards. Where I live the local radio station & also the Humane Society shelter will
take (post) ads for lost & found, and ads in local paper might also be effective. Sadly though, this snake may have been dumped & is unwanted.I wouldn't
plan on an owner showing up, though someone may say it's theirs just to get a free snake (& probably won't take acceptable care of it). So if you advertise finding
it, I would be vague ("found snake, owner must describe to identify") and you'll want to be sure they know the species, the size & any unusual markings before
releasing it to them. If you cannot care for this snake, it's also possible you could find a new owner on this forum...with any luck, someone here may be nearby.
I'm glad you're doing the best you can for it, but it might be wise to check around for a herp-rescue in your area if you cannot afford medical care for it. Vets
should know about that...call & ask. It sounds like it has a respiratory infection ("RI") and for that it's best to see a vet...he'll need meds (injections) to clear that
up. Do NOT underestimate a "cold" in a snake...they cannot cough so the secretions mean they are struggling all the time when trying to breathe...that's why he
is "mouth-breathing" & an RI can be fatal. IF this is very minimal, some snakes can recover on their own with good conditions (cage temps. a few degrees above
normal range) but don't count on it.
A normal healthy ball python should be housed with 78* at the "cool" end of the cage and 90* at the warmest. It's really crucial to get temperatures correct,
which means an accurate way to measure them, otherwise a snake can get a thermal burn if the temps. are too high. They don't always know when to leave
a spot that's too hot, so while I suggested temps. a few degrees higher to help his RI, it's crucial that you don't exceed 91*. Because he was so cold outside,
it's just as well that you started off a bit low (70-85*) for temps, as coming in from the cold as he did is a bit of a shock. (how cold is it outside where you are?)
And thank you for trying to help this poor snake!