Hi
Welcome to the MedHelp forum!
There are many causes of dizziness, lightheadedness, passing out, blackouts etc. It is difficult to comment without examination. I am just enumerating the possible causes. You can discuss this with your doctor and get yourself examined. Dizziness could be due to postural hypotension (blood pressure falling with change of position), internal ear problems and cervical spondylitis or compression of cervical spinal nerves. All these cause dizziness when you get up from lying down position or when you change position that results in a change in the level of your head. Cervical spondylitis can also cause back aches.
Other causes are anemia, claustrophobia, GERD, hypoglycemia or low sugar and some endocrine problems. Endocrine problems, such as an underactive thyroid (called hypothyroidism), overactive thyroid (called hyperthyroidism), adrenal insufficiency (called Addison's disease), low blood sugar levels, and in some cases, diabetes, may lead to hypotension and hence lightheadedness and an off balance feeling. A comprehensive investigation is required keeping all the points in mind.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!
Aside from the back pain, I'd say get your iron level, ferritin, and TIBC or total iron binding capacity checked via blood testing, because the other symptoms could be related to iron deficiency anemia. You also may want to get checked at the gyn to see if you have a hormonal imbalance. And, get your orthostatic blood pressure and pulses checked (lying down, sitting, and standing) to see if there is a big fluctuation in pulse and or blood pressure. What part of your back is hurting?