Help! My lovebird has suddenly turned on my family! Read info?

We got him three weeks ago and he was six year old, He was hand reared and was fed baby bird food off a spoon, and ate seeds out of his bowl. He was so cute and loving for the first 2 weeks, I couldn't not be with him for like an hour except for being asleep. last week I went away for 5 days too Nsw and Mum spent every second with him instead of one day when she went to work and I got back last wednesday and he was so happy and jumped on my finger, and was so quite and cuddly and gave us kisses. The next day he suddenly turned weird, started biting and holding on, chirps constantly, doesn't let us touch his back, or scratch his neck, he will just bite, and when we give him kisses he just straightens up and leans backwards. Is he scared of us or something we do? I can't think of what we've done wrong. We went out 2 days ago too buy him a happy hut bird bed, and he sleeps in it and he's very warm, we also got him a mirror with little bells he can play with. We let him walk around the house but now he doesn't leave his cage. He's just so selfish and mean now.