Just thought I'd post an update on here as people have been so kind to reply to my posts in the past & in case this helps anyone else in the future.
After being unwell for 8 months & in hospital for 6 months, we've finally received a diagnosis of fungal meningitis so the correct treatment can begin & he's starting to seen a bit better.
Although this was suspected fairly early on & then dismissed after 5-6 months of treatment (as they thought they'd have seen some improvement by that stage), fungal meningitis has been found (plus some bacteria but they're not so concerned about this). The reason for this is he was also being treated for everything else ie tb, bacterial & viral that the fungal treatment was not being sufficiently absorbed & therefore not effective.
Turns out that aspergillus was the cause. A very common fungus but very unusual to cause meningitis. Eventually diagnosed by a biopsy.
No idea about recovery times, but this is a start which we've been waiting a long time for! Good luck to everyone else continue to battle this difficult illness.