The green line is over what looks like a ‘pannus’ and the purple dot shows that the posterior arch of your C1 vertebrae may be slightly more forwards than it should be, these both suggest some cranio-cervical instability. The yellow lines indicate a loss of ‘lordosis’ of the upper cervical spine.
You may have collagen issues or you may be blatantly hypermobile, or you could have had an injury at some point in your life that was more serious than you thought it was. Either way you have to consider how to manage this. Any injury needs bracing immediately (trust me on that one!)
I suspect that your symptoms are variable, sporadic and intermittent because this is what is usually found with this kind of condition, as whatever part of the brainstem/spinal cord is irritated depends very much on your head position and degree of tilt. Symptoms can also be exacerbated by any degree of raised intracranial pressure.
You need loads of vitamin C to help repair defective collagen and I don’t mean gulp down a pint of orange juice because, your body does not store vitamin C apparently, so only a little will be used and the rest will be wasted. You need to take a little and often throughout the day, to give your body a fighting chance.