According to the symptoms you described, you might suffer from postural (orthostatic) hypotension. It is a disorder of the neuro-vegetative reflexes for fast blood pressure regulation. Failure of this mechanism leads to hypotension and decreased brain blood flow when the body changes position from horizontal to vertical. Besides standing up slowly, there are also some medications for this condition like “dihydroergotaminum” or “etilefrine hydrochloride”. Ask your doctor for this and control your anemia, which can also contribute to these symptoms.