On the word "mejor"...
From a tutorial (I believe on this site...) I was led to believe that "mejor" refered to the opposite of "joven" ... So I thought it referred to old age.
I see in page 66 of Madrigals that it refers to better, as in a patient got better.
"El paciente esta mejor"
You have seen: mayor
Mayor means older.
Soy mayor que tú. I am older than you.
it is also used for the elderly,
Es una señora mayor.
How about "mayor" as an opposite of "joven?" I think that is what was intended...
(=de más edad) older
My book "Anda" says that mayor is the opposite of joven. Mejor means "better" or "best". "El paciente se mejora"
I think you may be confusing "mejor" with "menor". Although "menor" is not the opposite of "joven", but rather similar.