Can a NOL be carried back to a closed tax year if it occurs in an open tax year?

I am amending my 2016 return and now have a Net Operating Loss of almost $15,000 from a new business I started after being laid off from my job. I would like to carry back that loss because I had substantial income while employed and it may take a couple of years for my new business to show a profit. So the refund would be helpful. It is my understanding that when you carryback a NOL it has to go back 2 years first and then be carried forward if any loss remains. However, it is 2018 now and tomorrow will be the cutoff time for statute of limitations for 2015, and 2014 is already closed. I believe this is a somewhat complicated computation and would like to hire someone to help me with it to make sure all is input and calculated correctly. 

So, my question is, will it be possible to carryback the loss to 2014 and 2015 even though they are 'closed' tax years if the loss is discovered while amending an open tax year, ie: 2016? If so, then I have time to make sure the calculations are correct by finding help. If not, then I will attempt it myself and only go back to 2015 and then forward.

Please help me with instructions if that is the course I am left with. For example, Do I just amend 2015 with a 1040X? 

I have been searching for hours for a question similar to mine, all over the internet and can not find any answers and now feeling a lot of panic.

Your help is much appreciated.