I left my cat at the house for 2 months by himself. MORE DETAILS BELOW!?

I left him my cat alone for almost 2 months because I have been staying with my parents for personal reasons. I check on him at-least 4 times a week most of the time 5-6 times a week. I have noticed lately (this week) when I come home to feed him and visit him he follows me around and keeps licking, and smelling me also he is stalking me. Then today he kept lunging at my neck and trying to bite me. I wondered if he is turning feral. He only has access to outside when I'm staying home for more than an hour. He always has food, and water. Does anyone know what this could mean?