beta
Its delusional misidentification syndrome, specifically capgras delusion, which someone hold a delusion that a loved one has been replaced by an imposter. Usually they think it's an doppelganger, or some stranger in disguise, but sometimes they also think it's an alien, shapeshifter, monster, ghost or something along that lines.
Or maybe, he used himself as a test subject for project apple and gain some superpower. But Melinda think the changes is because he is replaced by an alien.