I would suggest finding a compounding pharmacy. Chlorquin is a human drug used to fight malaria in the past. Most strains of malaria are resistant to it now, so it isn't used much anymore. I think it's still fairly readily available in Australia, and a few other places like maybe Brazil. Not sure the problems with ordering drugs from overseas, but it might be worth a try, too. I'd just do an internet search on "Chlorquin", or "CHLORPROMAZINE" and see what comes up.
The most likely intracellular parasite in this case, I think, would be the coccidian Haemosporidia spp. That would warrant treatment with Chlorquin or a related anti-malarial.