In my middle finger of the left hand there is a small bulge that appeared five years ago it started to grow last two years and it's rigid ?

Your young age: leads me to suspect some things more than others. You may have experienced some trauma which was the cause of the initial bulge. Perhaps a cyst has formed around it and scarred. Less likely is an arthritis lump (rheumatoid or osteoarthritis) or a ganglion cyst. Since it has been there so long, I suggest a Doctor visit .. either first to your PCP or an orthopedist/Hand Specialist.