Why does my internal storage keep decreasing?

[AC Question]

The last two weeks I've only used my phone to play some games, maps, Gmail, talk, and text.
I haven't taken any pictures, videos, songs, or downloaded anything new
Suddenly a message pops up "Storage space is running out. Some system functions may not work"
All I do is talk and text. The next day I get a message "Your phone's storage is full. You won't receive new SMS/MMS messages"
I go into storage, delete pictures from Gallery, uninstall 2 apps. The text message warning goes away.
I try to reinstall one of the two apps I took out. It says there isn't enough room
1 hour later I get a message that says "Your phone's storage is full. You won't receive new SMS/MMS messages"
I haven't done anything. No call, text or use apps
The only thing I did is uninstall and delete.

 

[belodion]

What phone? What do your storage stats indicate as using storage in Settings, Storage? A screenshot thereof would help.
https://forums.androidcentral.com/showthread.php?t=409154