My son ate a pot brownie

Last night my son was with his friends and when he came home he was acting very strange. He went up to his room quickly and I could hear him pacing. I'm going to bed and he comes into my room panicking saying he's sorry and he ate a pot brownie and he thinks he's having a heart attack. I asked how much he ate and he said the whole thing. His friends had some and they ate them at the park. When he started panicking his friends left him there. I wasn't even going to yell at him. I was 17 once. I told him he wasn't having a heart attack and I got him some water and a snack. He already has anxiety so eating a whole pot brownie was not smart on his end. I ended up having to lay on the couch with him and rub his back because he was freaking out and eventually fell asleep. The next morning I sat him down and we had a talk. Weed is legal here (and I do smoke a little) and I told him why its best not to do it underage. But I also told him when he is of age don't eat the whole damn edible. You eat a small piece and don't get high with dumbasses who will leave you. Maybe it seems like I'm a bad mom for telling him how to eat an edible but I made sure to tell him when he's of age! And if he does do it again at this at least he does it safely. I dont think he will though because it scared him so bad lol.