Exactly same happened to me. get him checked and heed advice from above. my little guy started off loving me now he sometimes loves me and comes out and sometimes hates me. HATES me! I know it sucks... but they can be grumpy little things!
Maybe aggressive is the wrong word... he used to do that head thing remember? When he shake his head at me like i was telling me to go away! But he didn't do it today for first time in 2 and a bit weeks! X
Took napoleon out to clean cage. and instead of being aggressive he was wandering up and down my arm a lovely green colour! I think he likes me again!!
Thanks for all the advice guys. my little guy is only a 6 month hoe and im very worried about putting anything in that will hurt him. I'm very protective!