Hi traxtion,
I very much doubt that you are posting here "looking for information to feed and justify your anxiety" as suggested. You actually said "I'm feeling a bit spacy and have a very stiff neck and intermittent headache. I also deal with anxiety and know I could be manifesting these symptoms". You answered your own questions in a sense.

It's very common for people to be afraid of sustaining another concussion and some people even start avoiding certain situations. From personal experience that's never good for long term healing. Anxiety is also a possible symptom of the post concussion syndrome PCS so I don't know if your anxiety started after your concussion 2 years ago or if it's something you've always dealt with.

Those of us who deal with anxiety in this world do not go around public forums looking to "feed and justify" our anxiety"! Those of us with anxiety struggle to find understanding and freedom from symptoms, often lifelong, despite putting in all the hard work.

When the symptoms (flight or fight) of one condition overlap or are the same as a symptom of another condition, whether that be pre-existing or post concussion, then there's a need to sort it out.

In your case it's been 2 years post concussion. The dog hit is hardly going to hit your head or neck hard enough to give you another concussion, and you recognise that the symptoms you are having right now ae the same as when you have anxiety, then work on calming techniques and knowledge about what fear does to the body. Starting with the physical signs.

Look after yourself. Take measures to lessen your anxiety. Learn what anxiety does to the body and that can help you recognise what's going on. Learn how to breathe correctly.

Learn to recognise a bout of anxiety coming on just by being present in your body. Recognise that "aura" around you as your pulse rises, and your breathing is disrupted. Notice the perspiration on your hands.

Breathe.

Learn these signs and tell yourself that you are going to be alright. This will pass, but importantly if you continue to feel really off and need help, go to your doctor. That goes for any condition.

all the best.