It sounds like you have an app that is behaving suspiciously. You should restore as new again (which should temporarily solve your "Other" space problem). Then add well trusted apps back, like Google Maps if you have it, or other well known apps. Check your "Other" again - it should be fine. Then try adding apps that might be less trustworthy one at a time, let that configuration stay for a few days while using the apps, and check "Other" again. Eventually you will find the culprit.