What's going on?

I recently went from an pretty, slim outgoing, all smiles preppy and bubbly girl to a shy, chubby (and not to mention bald - alopecia) girl. All these happened in less than 6 months and I've been depending so much on my boyfriend for my social life and personal life and basically everything.

Lately he's been distancing himself, always busy with work or tired to meetup for lunch or that it's too much of a hassle to go.

I text him and call him but most of the time I don't get answers. He only answers when he texts me first and calls are practically non existent.

During weekends he stays over and becomes super sweet and all for a few hours and then tells me he's going to play games.

Is he losing interest? Is it because I'm no longer attractive? Because I lost my hair and gained weight? And because I basically just stay at home and cry? Only to get up for chores and for work? My head hurts and my heart is breaking thinking about all of this.