Can a punch to the head still affect me 6 years later?

[thebaseball20012]

6 years ago while sparring in a boxing ring, I got hit behind the head and so hard that the guy broke his knuckle on the back of my head. Old sparring gloves with poor padding. That night I went home and took a nap. I woke up with a full on panic attack and called the paramedics. I had never had a panic attack before and thought I was dying. The ambulance took me to the hospital where I had a CT scan done. No signs of concussion. That night I was sent home with Xanax. The next weekend I had another panic attack out of the blue. From then on, I would have them on and off and this is after a 38 years of life without attacks like this. These past 6 years have been a rollercoaster of meds, trying to get right again. The anxiety controls me so I treat that but then I get depressed from it so I treat that and I get anxious again, up and down but never really well.

Is there anything that could possibly be going on with me currently medically that would cause this? I know the diagnosis is anxiety and depression but I have to believe the hit to the head started this in motion. I always wonder if there is something else going on with my nervous system. I have had the normal check ups, blood work, thyroid checked, even MRI when I had headaches really bad for a month or so. Everything checks out. I just wish there was something I was missing that I could discover and get to fixing it.