I am worried that I may have a brain tumor

I am male and 45 years old.

For the last 8 months I have been having really awful headaches and forgetfulness.  In the last week or so I have fallen going up the stairs at the office and have banged into bins that I would normally have been able to avoid.  I did have a recent eye test and all was OK.  There also was a scan to detect anything from my eye and that came back OK.  Also been feeling nautius in a daily basis.

To put my life in context in the last 9 - 10 months I have had to deal with major stresses in my life.  My health I have really put down to stress but I can't shake the feeling that there may be something wrong with me and I don't want to waste people's time.  Today my headache has been the worst and almost paralysing.  I just wanted to write here when it's OK.  The constant headaches have been adding to my stress,