How to grab posts from the most recently created category

I have an interesting problem that I could use some help resolving.

I need to know if there is a way to grab posts from the most recently created category in WordPress.

My client has a magazine type theme going on. I am using the default category creation functionality of WP to allow them to create new "issues" each month. The category is actually the month and year. Think of a magazine, where for example the current issue(Category) is March 2015. They will create a new issue(Category) each month, and of course articles will be posted in sub categories of the current issue(Category).

How can I grab posts from the most recently created category for each month to display on the front end? This way in a table of contents it would look something like:

• March 2015 (Main, or "current" Category)
  
  
  
  • Sub Category
    
    
    
    • Article Title
    
    
    • Article Title
    
    
    • Article Title
    
    
    
    
  
  
  • Sub Category
    
    
    
    • Article Title
    
    
    • Article Title
    
    
    • Article Title
    
    
    
    
  
  
  
  

etc etc.

I am more of a front end designer and am unsure how to do this. Will this require custom SQL?

Any help or advice would be very much appreciated.

Thanks!