Hi Telmo,
An elevated CK, especially in the thousands, can be indicative of anything from a thyroid issue to a myopathy or myositis, and or juststrenuous exercise. I would not focus on it as a sign of ALS.
You mention that you "feel your muscles atrophying". Muscles atrophy over a long period of time from disuse, you don't feel it. For example, I had very well developed leg muscles, and I could see the muscle on the front of my leg pulling away from my shin, leaving a peculiar scalloped shape. That was months after symptoms started, not where you are. Here's a story for you.
When I first began to have symptoms, my doctor felt I had polymyositis (I presented atypically, and early stages can sometimes be similar to ALS). I hadn't heard of PM, so I researched it and actually began feeling those symptoms that are only true of PM, that's how obsessed I was, and I don't consider myself to be easily influenced by subconscious fears-yet I was.
I actually created symptoms that went away as soon as I had a positive diagnoses of ALS. And, incidentally, my CK was very low.
Please continue listening to your doctor, as Dr. Google cannot put your symptoms in context of a big picture for you.
All the best,
Liz