Charlie has been the sweetest dog until about 6 months of age. He started become food aggressive towards bones. We tried everything we could think of but nothing seemed to work and then the trainer we were working with for obedience training at his school said just give him the bone and don't take it away... 
Well... now he's been neutered and since the second day he started to become extremely aggressive. I understand that dogs can be aggressive for a few days after surgery due to not feeling well but Charlie never really... stopped. It's been 3 weeks now since he was fixed and his aggression is escalating. He growls at everyone. He starts to get stiff, his eyes go still and dilate, and he starts to give a low rumble. If you try to get near, he bares his teeth and growls louder. He first only did this when bones were around him but now he does it to anyone. He mostly grows when it's just me and him and someone tries to come near me like my parents... but now he's turning on me. I have no idea what to do and my patience is wearing thin because I have family coming in town next week for Thanksgiving. He loves people and he's great out in public... it's when he gets home the issues start to appear. I have 5 year old twins that are going to be running around the house and I don't want him to go off on them. Charlie is only 7 months old and I know I need to nip this in the butt. There is no way I'm getting rid of my kid either and putting his issues on someone else... he's my responsibility. I can't quite afford a behaviorist yet either being a poor college student. I have been trying to wear him down too through a lot of exercise and I mean... 2+ hours at the dog park... maybe another hour walk later.... and some training. I have him mentally tired but he still puts up a fight. I stood over him and growled back at him last night (I know I sound ridiculous) and he backed down but only during the time we were having our disagreement. My vet told me to start making him feel like he's the lowest of the low so I've been making my extremely shy and extremely submissive quiet sheltie go outside first before he can... feeding her first and making him watch before he can eat... making him sit and wait until I cross the threshold before he can... but he's still extremely angry. I want to cry at this point because he really is a good dog, I just don't know what to do next.