I'm really in no way qualified to comment on your experiences, only to sympathise in what must have been an unacceptable nightmare.
I'm only posting to say that in a distant recollection of when I worked for a large company pre '72, the only similar experience I remember, again Nigeria, the company doctor immediately had the patient, with similar symptons to those you describe, whisked off to a BUPA specialist tropical medicine unit, which presumably still exists. At the time we all thought it made the BUPA contributions seem cheap, and I can't remember opening an African operation being on the board room agenda afterwards!.