If i had a mri&ct 5mths ago of the brain can anything serous change from then? like coma or tumor or bleed i'm 20 with no medical problems

Unlikely if no sympt: At 20yo if no other medical problems or reason to be worried about these things then it is very very unlikely to expect anything new to b occurring. Your anxiety level about this may b more of an issue worth addressing. Coma is a clinical state of unconsciousness which u don't have since your are conscious. Bleeds or tumors would most likely be causing symptoms. Discuss your concerns with md.

Not likely: If you had both a negative MRI and ct 5 months ago it is highly unlikel that anything serious like a tumor or a bleed would be present. If you had a coma you would be unconscious

Unlikely : At such a young age it is unlikely that there would be any change in such a short time. If you had head trauma that could change the head ct.

Extremely unlikely: Extremely unlikely if you have no symptoms. A slow growing tumor or a clinically silent bleed are the most common possibilities, with an estimated likelihood around one in ten million in a healthy 20 year-old.