VLF count suddenly growing and unable to reduce it
The VLFs grow when the log grows 
When VLF’s are created, either by autogrow or a manual grow; a certain number of VLF’s are allocated according to the size.
&lt; 64MB will create 4 VLF’s
= 64MB &lt; 1GB will create 8 VLF’s
and > than 1GB will create 16 VLF’s.

This was prior to 2014. From 2014 SQL Server onwards this has changed and can read in more details here : Understanding increasing number of VLFs 

A few hundred of VLF is actually not that a big issue and you can re-configure your threshold. To fix this you can shrink the log file to the lowest possible and make it grow to a bigger size at once and then allow autogrowth if required. More on this can be read here : 

Fixing vlf issue

VLFs will always increase and only when huge in number will cause performance issues (thousands ).