The Meaning of Nothing

AP here:
Pondering the meaning of nothing.
I am not a big believer in nothing. I believe in cause and effect in which an action or event will produce a certain response to the action in the form of another event.
If you have ever studied philosophy or know anything about Karma you have heard of cause and effect - action and reaction.
In science this is one of Newtons Laws for every action there is an equal and opposite reaction, -something happens and something caused it .
In management cause and effect is used to predict outcomes and to locate potential problems within a process.there are even diagrams and charts to help narrow things down.
So what happens when you have an effect with no cause?

Something is causing Tonka's problems, something is having an effect on his ability to walk and balance correctly. I have spent 8 months now dealing first hand with this  "Somethings"   effects and am no closer to knowing what the cause is. Multiple Orthopedic Doctors,  Multiple Neurologists, many, many tests of different types and we have a big fat "Nothing" as the Cause.

The last place to look - his head and neck - was scanned using an MRI on Thursday evening.
His Canine Rehab Specialist (physical therapist) Chris came by to check on him and get the results first hand. She went over the results with Dr. McDonnell before I did and was with Tonka when they called me back. I could see her in the back on the floor with Tonka and was looking at her to see if I could get a read on whether I should be bracing myself for the worst. Dr. McDonnell then proceeded to tell me that Tonka has a beautiful head and neck and there is nothing visible that could be causing his symptoms.
Now I had joked with several people that this was my worst fear and you were going to have to pick me up off the floor if that was the verdict and here it was- a diagnosis of nothing.
I am sure my real reaction would have been puzzling to anyone not knowing the full story or the past 8 months.
I had just been told that there is nothing nasty lurking in his head and most people would be ecstatic and jumping for joy instead I was just dumbfounded. this was the last place to look - the answer was supposed to be here - good or bad we would know something.
Nope - nothing there - nothing to fix - no cause to his effect...

So what is the meaning of nothing? and just what do you do with nothing?

Chris and Dr. McDonnell had the only answer I can hold on to at the moment which is to "keep doing what we are doing". He has come a long way in 8 months so that is what we will do..