Upset tummy

Hey ladies, my little guy is 12 weeks old and has been spitting up non stop the past week or so and his poop has been green but recently has had more mucus in it. From what I've read online it seems he may have a gi infection. Anyway it's Sunday so the clinics here are closed and will likely be tomorrow as well for the holiday. It's this something you'd bring your little one to the hospital for or should I just wait until Tuesday? I don't want to have him around all those unnecessary germs if I don't need to!

Also is there anything I can give him to help besides gas drops or gripe water, I've tried those both.