Oh my goodness. First, calm down. Second, my little 23 mo old has been sick with the same symptoms your son has for the last 4-5 days....exact same. I think maybe something is just going around. Same green loose and sometimes watery stools, same throw up, same congestion, same runny nose. Of course teething is teething. I think it is just an infection that is being passed around -- my kiddo probably picked it up from his part time daycare or a park. He seems to be feeling better this morning. We took him off all milk for those days and gave him only water and easy bland foods. Anything else made it worse.
Just get an appt for tomorrow and if it gets much worse, do a walk-in clinic at a hospital or the kids ER if you think he is dehydrated (if you have those out there in CA--they had peds ERs here in the Chicago area).
Unfortunately those take-care clinics like Walgreens and CVS do not generally take kids under 18 mos or 2 years I believe -- even for ear infections.
Best wishes!