wonder when it started

Just two years ago, on summer vacation with my sister, niece, and great-nephew, I was still pretty active.  The only real discomfort I felt at the time was from the breast expanders I had in me since the double mastectomy.
I was able to take a running start to jump into the pool, and did a great deal of walking the day we went to Hershey Park.

Even last year, I was still doing pretty good when we went away in the summer. That was several months after the reconstruction.  I was able to climb the ladder to use the pool slide, and spent many hours playing around in the water.

There was just one day, I remember, when I was in a lot of pain, and spent most of the day in bed.  Other than that, I was doing fairly well, considering.
It was soon after the reconstruction reversal this year, in March, that I started to really go downhill.  Of course, the pain (mostly in my abdominal area) had been persistent for fourteen months.  But then the breathing problems really came to the forefront, which of course precipitated that first hospital admission, where the diagnosis of breast cancer metastasis was made.
Prior to the admission, I'd started having bad leg pain, which I kind of chalked up to on and off leg pains I'd had most of my life.  Since I was a kid, I'd suffered with bad knee pains at various times in my life, and though this pain felt more severe, and involved my entire leg, not just the knees, I didn't think there was something more ominous going on.  Little did I know that I was now experiencing painful metastatic bone pain.
Had I not gone to the hospital because of my breathing problem, there's no telling how long I'd remain undiagnosed.
I wonder when the mets started. 
I had the PET scan back in April or May of 2014, after chemo was completed, but before radiation started, and that's when they told me I was cancer free.  So, sometime within the next two years, the metastasis developed.
I have been on some kind of pain control for the past year and a half, now taking oxycodone every 4-6 hours.  Sometimes I try to do without it for a few more hours, but pain comes back full force, unfortunately.
Recently my legs have started to get very numb and painful soon after standing up.  Feels like a thousand rubber bands gradually tightening around my legs from my feet to my knees.  Almost makes it impossible to walk.
Worse than the pain is the breathing problems, which don't improve much at all.  I can't walk more than half a block without stopping to rest.  This keeps me more or less homebound.
Yesterday, I went to the cancer center to get the injection for my bones.  Turns out my calcium was low again, despite taking a calcium pill and calcium carbonate oral suspension every eight hours since being discharged from the hospital last month... so, I was unable to get the injection.
Next week I have to go for an IV calcium infusion, which will take two to three hours, hopefully improving my levels, so I can continue with the injections.
I worry about the effects on my heart, since the low calcium caused me to have EKG changes.
I don't understand why my calcium is so low when I'm taking so much stuff to regulate it, and haven't had one of those injections (which causes the levels to drop) in about two months.
What the fuck body?  Why aren't you cooperating?