Left rear indicator failure/ brake light issues

[Southfl]

Have a 2015 Silverado and the left rear indicator failure alert recently came up. The top bulb was not working so I replaced it and neither the top or bottom  works now. Brake light also does not work now. Just the white reverse light. Next step to replace wiring harness to that light??? 

Only the top blinker light did not work until I took the bulb out to replace. No corrosion noticed on the bulb connections. 
 

Also, just noticed the top brake lamp on the top of the cab is also not working. I’m assuming it just started not to work, but I qm

not completely sure. Checked the fuses and did not find any blown. 

Thanks for any help

[Southfl]

3rd brake light was just a burnt bulb. Working now. Still trying to figure out why the rear drivers turn signal and brake light are now working