If you are experiencing dizziness, the answer could be any one of numerous causes or a combination of them. 

Commonly, it is a vitamin B-12 shortage.  Read this carefully....In the lining of the stomach there normally is a colostrum-like sticky substance called the intrinsic factor.  Its purpose is to bond with water soluble vitamins and specifically vitamin B-12.  Without the intrinsic factor, vitamin B-12 is not captured well and it is typically urinated out or lost.  Vitamin B-12 must bond with the intrinsic factor to ultimately penetrate into the bone marrow where red blood cells are formed.  Without the proper amount of B-12 in the bones for the RBCs to form accurately, they are distributed into the body in varying sizes.  These large and small RBCs are supposed to be the same size to function accurately.  The varying sizes of RBCs can cause lightheadedness, dizziness, weakness in the muscles, and lethargy or tiredness.  Some people genetically have acquired this problem from a family DNA trait.  Others that have digestive issues have perhaps caused an upset or waning of the intrinsic factor.  These digestive issues could have stemmed from improper nutrition in eating habits, too many spicy or hot foods, alcohol consumption, etc.  Some people have to receive regular intramuscular B-12 injections to get it effectively into their system.     

Those individuals that have had bariatric surgery of a gastric bypass have taken away most of the intrinsic factor by virtue of taking away most of the stomach lining.  Vitamin B-12 shots for these individuals will be imperative throughout their life. 

While studying in Japan many years ago, I discovered that high amounts of Folic Acid or Biotin will substitute very well for the intrinsic factor.  For people needing this additional process, anytime vitamin B-12 is taken in a supplement or vitamin B-12 foods, Folic Acid or Biotin should always be taken with them for proper bonding and assimilation.  Folic Acid daily at around 800-1,000mcg or Biotin at 500-800 mcg will act as an effective "intrinsic factor" alternative.  Folic Acid or Biotin are also water soluble and have no side effects. They are totally non-toxic at high levels but necessary for Vitamin B-12 absorption for some.

Anemia or an iron shortage can cause dizziness.  Too much iron can do the same.  This would have to be determined by a health practitioner by performing an hematocrit or hemoglobin test. 

An on-going illness or the flu can have the dizzying effect.

If you are somewhat inactive and are not accustomed to certain activities that change your equilibrium, you may have to to some active things to acclimatize to the head shifts. 

Some people get dizzy with high blood pressure or conversely low blood pressure.

Some people get dizzy with elevated glucose levels or low blood sugar.

Vertigo, as it is called, also has a host of causes.  There are treatments by practitioners even though difficult that can assist in "seating" the crystals in the inner ear that otherwise cause dizziness as they float around.  A virus or bacteria at some point in life can cause inner ear damage and issues. Often these problems can be long lasting.   Loud noises or banging can cause injuries to the inner ear that can be permanent.  Shotguns, high powered rifles or other painful sounds without hearing protection can lead to problems.  

Some prescription medications for some may have a dizzy side effect.

Chiropractors will let you know through x-ray examination or manipulation if there has been a subluxation or shift in vertebra to shunt the blood and nerve supply to the brain.  There's a small natural hole in the base of the skull where the second cervical vertebra has a protruding bone that sets vertically through the first cervical vertebra and into that skull hole.  If the second cervical vertebrae is rotated or tilted, the bone called the odontoid process which is a part of the second vertebra, can put undue pressure on one side or another of the posterior brain in that skull hole causing dizziness.  Sometimes a kyphosis or rounding of the shoulders can cause an unnatural angle of the vertebra odontoid process will cause this.  Postural correction may be necessary to correct this. 

Dehydration or the lack of water can cause dizziness for some.

Now the bad news....If you have gone through the winnowing process (if it's not this, it may be this, repeat, etc) there is the possibility of a tumor or cancer.  This too should be determined by tests completed by a health practitioner.