I would definitely go back to this person’s health team and make sure everyone is communicating. You need to know how many members of his health team are giving him prescriptions and verify that everyone knows everything that he is taking. And also communicate with these doctors about what is happening during his exercsie sessions. The team may be able to adjust his medications and/or adjust their advice to you about how to handle the side effects during exercise.
It is also important that you keep the health team informed as things progress. I have found that my feedback has been indispensable in helping clients’ doctors, surgeons, therapists in adjusting the client’s treatment. We see the direct effects of treatment plans during exercise and this is important information that can sometimes be crucial to adjusting treatment.
Good luck with this client. Use this as an opportunity to learn and grow.