Hi, so my bp Nagini has been acting strangely for about a month now and I'm not sure what could be causing it. It happened roughly over night when I went to take her out for feeding and she snapped at my hand.
I've owned her second hand for a little over a year now and she has always had a sweet demeanour. Though the previous owner didn't know how old she was she was fully grown when I got her. I handled her regularly and kept her social with family. She originally feed on large mice every 7-8 days, usually refusing to eat any time before then, and went on a three-four month fast last winter. But now seems almost ravenous on large weaner rats and seems really thirsty.

Every time I go near her viv she gets really defensive and will try to get at me through the glass. She will let me put my snake hook in the viv and gently nudge her but will hiss if I try to hook her and quickly tries to escape. Cleaning the viv was a nightmare as I had to clean half, move her hide over, then clean the other half and move her hide back over again. lol

I haven't tried to handle her yet since I want to get some thick gloves in case she does bite me.
Her breathing is normal and she doesn't have mites. Her weight hasn't fluctuated much either, though she does seem to slowly be gaining.
I'm considering scheduling her a doctors appointment.

I've seen somewhere that this could be do to some type of defensive mating behaviour? Or that she could be reverting back to a sort of "wild state" of mind?
I'm just really at a lose and worried for her ):
She's my first snake and third reptile so any advice would be grand.
Thanks!