What Causes Pain And Tenderness In Finger Joints?

I am 43 and have been a mechanic for 25 yrs. the past few years, I have been noticing more aches and pains than usual, especially in my hands. For the last few weeks, my right hand has been the worst. The knuckle of my right middle finger feels as if there is a needle sticking in it. There is an especially tender spot in the knuckle towards my index finger knuckle. There is some lack of dexterity and at times I can not make a fist to where my finger tips touch my palm. suggestions or ideas what it could be or what I should do?