Hi,
Noted your history about your son developing blue lips and finger during running even, blood tests showed non-active mono, Cardiologist says not due to any cardiac problems.
This means there are other reasons for a runner to have such changes.
I would advise you the following:
Since he is a runner developing such symptoms is an indication for proper clinical evaluation, an actual examination of the whole body and thorough investigations are needed to find the cause.
Since cardiac evaluation has been done I would advise him to
consult a Pulmonologist for PFT and all necessary tests.
Hematological re-evaluation of blood tests can help further.
All these will lead to find the cause and thus get an appropriate cause.
This can then be treated well.
Surely, no running or such activities till the full diagnosis and management.
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. T. Chandrakant, General Surgeon