Dragons name- Spike
Type- I am unsure. He his mostly light orange/brown. His beard is dark orange, black and red. He has light brown striped horizontally from head to tail.
Size - aprox. 1.75 feet from head to tail.
Age- 5 years old
Diet- Crickets, Celery, Lettuce (mice, mealworms, hornworms as treats)
Environment - 3 Feet Long x 2 Feet High x 2 Feet Wide. 4 inch deep sand (red and black sand). Large fake tree in the center (top of tree is several inches away from one of his lights).
Has 2 Daytime lights and one Nighttime (red).
Average Daytime Temp- 35 Degrees Celcius

I have had Spike for about a year and a half. When I first got him, he was edgy, but got used to me.

About 3 months ago he snapped. He was sitting on my shoulder (as he always would) and my brother walked past him. (My brother was always very gentle with Spike and had never had any problems with him.) Spike flattened out and bit my ear. I then went to his tank and put him in. Ever since this happened he won't let anyone go near him. Every time I try, he flattens himself, flares his beard and viciously attacks my hand.

Is there anything I can do to make him calm down? Or is it just an age thing?