Unusual battery drain in Nexus 5X

Hello,

I would like to ask you about the strange battery drain that I have noticed with my Nexus 5X. I bought it nearly 1 year ago so it's quite new.
Without using mobile data, browsing internet and doing a lot of photos the battery stays 1 day ~15h.
That's very strange. I've noticed it after I was in the mountains. It was cold up there, snow etc.
Before the battery lasted up to 4 days without charging it. After that trip it has gone down first to 10h and now 1 day 15h.

So my question is have you had something similar? Any tips what could have happened and the most important one what to do with it now?

I'll be grateful for any advice.

Regards,
Justyna

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