There are more possible causes for your symptoms than we could possibly list. The good news is that most likely, it's not a brain tumor- there are hundreds of more likely causes.
I would start with a full check-up, including gyn. You may be in menopause, which would explain the hot flashes. Hormonal changes can cause headaches as well. Be sure to describe your symptoms to the doctor, and he or she will decide if a CT or MRI is warranted.
Stress and tension are also common causes for the symptoms you describe.
I'm not trying to dismiss your concerns- definitely get them checked out. But know that more likely than not, they are due to a common or benign cause. Good luck and I hope you get relief soon.