Why did I suddenly lose so much space on my internal storage?

[Android Central Question]

I have about 16GB of storage on my android phone, a Vivo 1609. I had about 76% of the space used last night, and this morning I woke up to find that about 97% of it was full. Obviously I didn't download anything. I cleaned out a few files and reduced it to 91% but I want to understand why the storage suddenly dropped 20% overnight. That's f@$%ed up.

 

[mustang7757]

Does anybody know why I would have lost 20 Gb overnight though?
But thanks for the tips. I'll be doing some trimming in the next few days.

That's the best way to do it , moves the videos / pictures like I mentioned earlier

 

[Stefan81]

sorry, I meant 20% sudden fill-up (76% to 96%). I had about 7Gb of room the one night and 850 Mb leftover the next morning.

 

[B. Diddy]

What about my question re: streaming media? Had you been doing that?