This has been bothering me lately. What are the differences between PTSD and PCS? How would I know if I have either one?

You have PCS. Your increased struggles with anxiety mimic PTSD but are not necessarily PTSD. Some believe prolonged concussion symptoms cause PTSD. I am not in that camp. PCS can cause so many of the PTSD symptoms that doctors struggle to discern a difference. PTSD can make PCS symptoms much worse. This is why help with anxiety is so valuable. btw. I was diagnosed with PTSD 14 years ago after being assaulted by a cop. It took a few years to recover but I can see a big difference between PTSD and simple PCS.

Have you been offered any therapy, such a CBT (Cognitive Behavioral Therapy)? It can be a big help. You think too much and need some help redirecting your thinking. You need help recognizing hoof beats as horses, not zebras. A good therapist can make a big difference in how you handle your thoughts.

Please try to get a referral/appointment with a therapist who understands CBT as it relates to PCS.

My best to you.

Mark put it very well. As a layperson who is injured you will not be able to tell. Good Drs do not treat themselves they know their perspective is not good for treating themselves.

I constantly seem to go back in time and "relive" the moment when I smashed my head on the wall. I always feel like I just hit my head and feel that "thud" moment and kind of nauseated afterwards. I think I have PTSD

I think you have regret. There can be a lot of anxiety caused by regret. PTSD is when the person injured had no control over the cause of the trauma or the immediate struggles that followed that trauma.