Sounds like your shift key is stuck.
Tap your shift key (both of them) with pretty firm taps. Maybe that will release the key so you can use your MBPro.
If you can actually get to your desktop, and open System Preferences, then the Keyboard pref pane.
Click Show Keyboard and Emoji viewers in menu bar. Not sure if that is the same in El Capitan, so you may need to look in another pane. Maybe in Keyboard/Input Sources. There will be a selection to show the keyboard viewer.
Click the viewer in the menubar, and you should see stuck keys immediately. You can try pressing each key on the keyboard, to check that each records presses, then releases when you release the key. The Shift keys will do the same when you press and release each one.
(I hope that the sticking shift key does not interfere with getting the keyboard viewer to appear, but I suppose it's possible, too.)