Q: MacBook Air keyboard not working properly

My MacBook Air keyboard types the front slash after I type the letters L, O, and the period. Then it begins typing the front slash non stop.  I can stop it for a second when i type a different letter, but it immediately starts again.  I pressed the "| \" button and it does not work at all. 

so this is what my notes look like at the moment

Jul\\\\\\\\\\\\\\\\\\\\\\\y\\\\\\\\\

Summer semester two\\\\\\\\\\\.\\\\\\\\\

stop.\\\\\\\\\\\

my macbook was purchased in September of 2015, and I had this same problem in December... but I somehow got it to stop. I have never dropped it, left it in the car, or dropped/spilled  anything on it or around it.

this problem is interfering with me logging my password into unlock the MacBook, my school work, and my general use.  can anyone help me??