Second Impact Syndrome has nothing to do with the mild impacts you suffered. You did not suffer weeks of head aches from your first concussion.

Second Impact Syndrome is where the brain has lost the ability to control fluid pressure (intracranial pressure, ICP) and suffers another trauma before regaining that ability. It is usually accompanied by severe head aches.

A concussion while suffering alcohol poisoning can be a double whammy. Getting wasted can effect the brain in similar ways as a concussion.

I suggest you not worry about your past concussions. Instead, you should focus on lifestyle changes to reduce your risk of future brain trauma, either physical or chemical.

And, stop looking for scary information. It only increases your anxiety levels.

"If I understand well another even minor concussion within the next 3 months could be fatal or make symptoms permanent, right?" Wrong.