Are you asking about impact tolerance improvement after 2 years or basic PCS symptom improvement after 2 years ? Are you still struggling with PCS symptoms ? What symptoms ? What have you tried to reduce those symptoms?

Nobody can say specifically what effect heading a soccer ball has. It does jar the brain and traumatizes the neck. I suggest you never head a soccer ball. It is not worth the risk. Soccer can be enjoyed without needing to head the ball. I would like to see soccer leagues where heading the ball is not allowed. Learn chest and foot traps instead. Research from the 1970's reveal a 9 point IQ difference between those who have a history of heading a soccer ball and those who don't.

Regarding running, try running a short distance with foam ear plus in. You will hear the impacts to your head. Then, modify your running gait and foot plant to reduce that impact. It will make a big difference. Nobody is going to say 'running damages the brain.' They would be laughed at. But, running does cause an impact force to transmit to the head. Each person will have different tolerances. Nobody can predict.

My best to you.