I need advice

As many of you know, I am a cancer survivor. I just got a text from a former teacher of mine from high school who tells me he is about to go through the same treatments I did and would like me to call him tomorrow to ask some questions. I really like this man but I am really stressing out over this. As you can imagine, that whole experience was a horrifying ordeal. I have tried to put it behind me and try not to think about it. I've even tried to completely forget about it. What if I can't remember important things? What if I give bad advice? I feel a level of responsibility here and don't know if I can help him.