For about a year my boyfriend has had head aches and dizziness. He has already had a MRI scan and nothing came up and has been to loads of different specialists and again they couldn't find a reason. Over the past year nothong more has developed and he has no other symptoms, if anything they aren't as intense. 

he had some bloods done recently and he said something was a higher than it should be and he wants to do a scan incase of tumours. 
 

brcause he has already had a scan and several different tests, we aren't sure why they would want to do another one. 
 

I need some help, to see if anyone would know why?