I read some where that Hyperbaric oxygen therapy typically is performed as an outpatient procedure and doesn't require hospitalization. If you're already hospitalized and require hyperbaric oxygen therapy, you'll remain in the hospital for therapy. How much [hyperbaric oxygen therapy cost](https://www.betteraging.com/hyperbaric/what-is-hyperbaric-oxygen-therapy/).
In the UK you can go to MS charities that have this treatment. Where I go, we donate and they hope for £15per dive, but will take patients who cannot pay that as well. I am in Yorkshire, and attend the West Yorkshire MS Centre, you can look it up, or search for others.
Good luck.