Would a headache caused by a brain tumor feel like it's on the surface of the head? Top left of the head, mostly when bending over, but not everytime

Please don't worry. Thankfully your history does not suggest a brain tumor. The human brain has no pain sensitive structures and thus brain tumors present more commonly with other neurologic symptoms or seizures. You should have a neurologic evaluation to set your mind at ease. Good luck and get well soon.
Parietal or temporal. Headache can be related to a TMJ dysfunction and sometimes the origin maybe coming from the occipital muscle. If a person is in a lot of stress, contraction of the muscle in a deranged side of the jaw can trigger a headache. See your M.D. Who can refer you to a neurologist and if your blood test, exams, and other diagnostic procedures came out (-), see a TMJ doctor.