My 15 Y/o Son Has Started Taking Isotretioin. He Is

My 15 y/o son has started taking isotretioin. He is into his 2nd week of therapy. Today, while at school, he was in his cross fit class exercising pretty hard. He ended up vomiting, then continued to exercise. He went to see the school nurse. His heart rate was 146 bpm and it took nearly an hour for his resting heart rate to come down to 108. His oxygen level was 96%. His BP was WNL. Could you please tell me what you think?