Hi Jude, Kimberly here from landscape-solutions-for-you. Thank you for asking your question on your apple tree.
There are many possible causes for why the fruit has black spots. It worries me that your apple tree is not stable in the ground. This could be signs of a damage crown or trunk area. The crown is at ground surface and below. There are factors that can cause this.
1. Wet soil and poor drainage
2. Cold Ingury
3. Soil and other diseases
4. Borers and other animals
The black on the fruit could be a result of one of these problems or black spot disease, which engulfs the fruit and leaves.
You can loosen the soil and take a look at the crown and below. Check out the roots and soil moisture as well as the color of the bark. Take a sharp small knife and scratch the surface of the trunk. The outer layer of the trunk may be brown in color, but a healthy tree will show signs of green. If the inner layer is brown or black the tree is under stress and could be dying.
If you are unsure of what to look for around the crown or roots, and have a local nurery nearby, I recommend going to them bringing a sample of the fruit and describing your situation. They should be able to help you out. If not, many professional landscapers will check this out for you free of charge.
I hope this helps some and please let us know what you find out. With the loose trunk, it does concern me, even if the soil may be firm. The temperatures are dropping which will cause the soil to firm up.
Thanks again for asking the question on your apple tree. Feel free to ask anytime here at landscape solutions for you. Good luck and have a great day.
Kimberly