What Causes Sudden Stiffness In Legs And Arms?

Hello, For a long while now I have be suffering with variable degrees of stiffness, It was mainly in my legs, walking, getting up from chairs & particularly walking up stairs, so much so that I have to stop as I cannot physically move. Also in my hands & fingers, where I feel like my fingers & thumbs completely lock for minutes at a time. It has recently affected other parts of my body. I am 23 & it has been happening for years. I have been too embarrassed to say anything to anyone before now, but it is very embarrassing when people stare at you because you are unable to move. I am overweight at the moment, but I wasnâ??t before & this doesnâ??t seem to have any affect. Please can you help or suggest something?Thank you