How to becom fair ? my skin color has changed?

b4 i was staying in cooler place,so i had nic color, but aftr marriage, i hav com to very hot region,and water has changed.bore water. i ***** tolerate d heat,and drastically my skin tone has completly changed. i luk so dark.b4 i was wheatish.plz help me..any advices.. even itchign sensation is ther..im relaly worried abt my skin and skin color...even my hair is falling bcoz of chang in water. plz help me