All belief or disbelief aside, please trust your medical care to your doctors and have faith in God.
A psychic can't prescribe meds, get you an X-ray or MRI. They have no capacity to identify what is life threatening or not. Even if they can speak to Aunt Tilly, was Aunt Tilly a doctor in real life?
If not, then you're extending your belief that - not only can this person speak to dead people - but to now include the concept that dead people have acquired the sum of all medical knowledge.
And let's even assume all of that to be true, what doctor is going to treat you or even look for a disease based on the word of a psychic medium?
Down that road lies only madness.