I seem to have a problem with my two year old male Dachshund, Rocky. I think he's developing aggression problems

. I don't know why either, as up until a few months ago he had never shown any signs of aggression. He was always friendly and social.
He has two problems...one is possive aggression, it's not that bad for the most part but occasionally when he has something he really likes he turns...viscious. Just now he broke through the baby gate and got into the kitchen and got a pizza crust. He wouldn't let anyone near him and he tried to bite me, my brother, and my dad. I tried putting him in his crate and he went crazy snapping and barking at me. I managed to get him in, holding his muzzle the whole time. I've never seen him like that before and it really, really worries me which is why I posted

.
The other problem started only a couple weeks ago. He growls and sometimes snaps if he's comfy and doesn't want to be moved. For example, a couple times I tried to put him to bed but he was already resting on the couch and he'd turn aggressive.
*sigh* I don't really know what to do. I suppose I should look into getting a behaviourist but my parents don't seem to think he needs one and I really don't have the money.

Is there anything I can do?