It possible he needs more salt, so try two mugs of Bovril per day or even better a stock cube dissolved in a mug of boiling water.
If the issue is salt an improvement should be seen within a few days, then you can make bone broth with added salt instead of using a stock cube.
And see the GP for a full test of blood tests, also maybe worth stopping the satin to see if that helps.
If the issue is salt an improvement should be seen within a few days, then you can make bone broth with added salt instead of using a stock cube.
And see the GP for a full test of blood tests, also maybe worth stopping the satin to see if that helps.