Error/Warning – .PHP Templates

Site: Uncustomary.org

Today I started receiving error messages on my Dashboard and anytime I tried to save something (page, plugin, etc).

The errors I get when I save are referencing my functions.php template and then options.php

This is the exact error message showing at the top of my pages on my Dashboard:

Warning: Cannot modify header information – headers already sent by (output started at /home/uncustomaryart/public_html/wp-content/themes/artsandstars/functions.php:2) in /home/uncustomaryart/public_html/wp-includes/option.php on line 748

Warning: Cannot modify header information – headers already sent by (output started at /home/uncustomaryart/public_html/wp-content/themes/artsandstars/functions.php:2) in /home/uncustomaryart/public_html/wp-includes/option.php on line 749

I did add Related Post and “Pin It” widgets today, but they’ve been deleted and deactivated (respectively). I’m desperate for help! I’ve gone through other similar posts and tried seeing if they’d be a solution for my problem, but I’m coming up short.

Edited to add: When i save anything on the Dashboard, this is the error message:
Warning: Cannot modify header information – headers already sent by (output started at /home/uncustomaryart/public_html/wp-content/themes/artsandstars/functions.php:2) in /home/uncustomaryart/public_html/wp-includes/pluggable.php on line 1178