Per your description, those spots are most likely a fungal infection most common at ages 15-24 years old called TINEA FLAVA or also called TINEA VERSICOLOR. It can be easily treated with antifungals like Selenium sulfide lotion or Ketoconazole.
You can find more information here: http://www.emedicine.com/derm/TOPIC423.HTM
Confirming it by seeing a doctor of course will be the best advise.
Happy New Year!
You can buy NIZORAL either dandruff shampoo or ointment that contains KETOCONAZOLE 2%, that is available in some pharmacy over the counter or in some grocery stores. Apply to the affected skin daily for 2 weeks (if using the shampoo wash off after 10 minutes).
If no improvemenet, then you will need the prescription medicine such as KETOCONAZOLE tablet.
( Experiencewise, the use of SALICYLIC ACID solution (over the counter too) is very effective. Moist a cotton with it and rub gently on the skin twice daily. It gives burning sensation, but in one week time it will start to peel off and it is cured. WARNING:It is at your own risk if you want to give a try but I had proven its efficacy several times without any apparent side effect.)