A Spanish book on witchcraft?
I wouldn't put much stock in one of those, especially if it's based off older information, the Spanish inquisition was inspired by the church and any "odd" marks were construed as "witch's marks" and justified the burning, torture and hanging of many perceived witches. More than likely it's just an anomaly in your eye and not really that uncommon, unlike two different colored eyes.
what exactly do you mean by "witchcraft like things"?
The Latin culture has an entirely different attitude towards witchcraft and demonology than the more modern, western worlds like America, not all witchcraft is demonic and demonic environments are rather volatile, I'd pay more attention to certain behaviors and energies around you to decide if anything serious is happening, the human body has a wide variety of physical differences that have very tangible reasons for being and don't necessarily mark anyone as a witch.
