Since my mom's death from brain cancer 5 yrs ago, have become fearful/preoccupied w/health. normal reaction? how do i overcome my fears/preoccupation?

Check up: See your doc for a check up and believe what he/she tells you.

Anxiety and death: You may have developed an anxiety disorder related to your mom's death from brain cancer. It may be very helpful to find a psychotherapist with whom you feel comfortable talking freely about your feelings and fears. Cognitive-behavioral psychotherapy specifically is often helpful for the anxiety symptoms you describe. Some types of medication might also additionally help.

Excessive fear: Being fearful/preoccupied with health 5 yrs later sounds excessive. While reading up on health issues (learning facts) may help somewhat , therapy may help more. A cbt therapist can help you challenge catastrophic thinking about health, while a dynamic therapist could help you explore lingering feelings or conflicts about your mother's illness and death that continue to haunt you.

Just: By asking ur question, u are already starting the process of overcoming ur fears and preoccupations with health. It is very sad u lost ur mom from brain cancer. Most likely, ur current fears and preoccupation w/health are part of your grieving process. I would kindly suggest u to find a good therapist to help u achieve closure w/ur loss & move on w/ur life. My condolences & best wishes to u.