Regardless of the cause of your difficulties, perhaps you could be helped by therapy and/or medication. As for whether the incident you related is the cause of the problem, I guess it could be. You mentioned that you had been distracted by your friends, so you probably blamed yourself for what happened and harbored guilt feelings thereafter. In addition to fearing that your brother would die, you may have feared how this would affect your parents and their feelings for you. Also, you mentioned having had the responsibility of taking care of your siblings. Might this have been a burden on you and resulted in some resentment or similar negative feelings which made you feel all the more guilty for having been distracted? Did family relationships/dynamics change after the incident - did your parents hold you responsible and did they treat you differently? I'm only raising these matters to suggest that there is much more to the near drowing event than the fact that it happened. To assess its significance in your subsequent emotional situation probably requires a look at the broader picture. I think anyone other than a psychiatrist or other competent mental health professional would just be guessing in offering an opinion as to what has caused your difficulties, which now apparently are manifested by panic attacks. Please consider professional attention and good luck in overcoming the problem.