This minor patch was an attempt to make a shortcut for an issue with the game not registering the newly added player stat "Oxygen", by simply deleting prior saves that did not have it, but it created more issues than it fixed.
If you go swimming for the first time and you find yourself immediately taking health damage, I recommend storing your belongings in a storage box, and letting the water kill your character, then restart the game. It wont happen again after that.
Or simply go into your C:\Users\------\AppData\Local\SCLPUE55\Saved\SaveGames and delete everything there to start a fresh save (oxygen included)
My apologies for the inconvenience