Consider a person who is not a medical professional but spends a substantial amount of time taking care of someone close to them suffering from a medical condition such as Alzheimer's disease or cancer. In Finnish we have the specific term "omaishoitaja" for this purpose. I am not aware of anything closer than "caregiver" in English.
How could one describe such a person in Latin? It does not have to explain the situation unambiguously, but it should be a suitable word when referring to such a person. The best words I can think of are curator and custos. I added further thoughts as an answer, and I would be happy to see more ideas if there are any.
(To make this searchable, let me repeat the main question in Finnish: Miten sanotaan "omaishoitaja" latinaksi?)