Complex sentence: Cusamano reassures Carmela that she does not have lupus, but most likely mono; he also checks after her mental health regarding any significant changes in her life that may have brought on this illness.
Split into simpler sentences: Cusamano reassures Carmela that she does not have lupus, but most likely mono. He also checks after her mental health inquiring about any significant changes in her life that may have brought on this illness.