Dwarf Hamster changed behavior

[VladimirCuten]

Hello-
My Russian dwarf hamster has recently changed his behavior toward me and it's been concerning me.
Vladimir is a 1 year old dwarf. When I first got him, I allowed him time to adjust to his home and me, and eventually he warmed up to me. He never bit me or was very skittish around me.
As of January, he has been acting quite differently. He charges me when I place my hand in his cage, he will bite hard on my hand and not let go, and even bites my arms or any skin he can find. Hes now super skittish unless I'm giving him treats.
He has no symptoms of illnesses im aware of and I feed him regularly. I did buy carefresh bedding from petsmart for the first time around December, it was blue and got all over him the first time I put it in, making him blueish so I gave him a sand bath and now use white bedding. I was thinking it was the bedding or something but his behavior hasn't changed. I love him to death and just want my fun cute Vlad back!
Please let me know if you have suggestions. I've tried reintroducing myself to him and have done the bathtub method recently again but no luck. Please help me understand my poor baby. I feel like a terrible mother.

[cypher]

Has anything else changed at all in or around the cage or environment? It is unusual to see a change like this unless something has changed or upset them or they're unwell in some way.
Did you do a complete clean when you changed to the blue substrate than again when you changed to the white? It could be a case of too much cleaning if nothing else has changed & he isn't unwell.

[VladimirCuten]

No usually I change it not super often. But could it be rearranging the stuff in his house? And if that's it, will he go back to normal?