Dear friend.
Thanks for sharing your concern.
Green colour is due to bacterial activity there in the mouth.
According to your history given it appears, it is erupting third molars,which is causing this infection.
Here i would advise you to see your
dentist soon ,get an
x ray done and if required get the tooth extracted.
This tooth neither serves the purpose of chewing nor esthetically required.
But, in turn it gives lots of problem as it erupts partially and harbours numerous bacterias,
plaque and thus recurrent infection.
Therefore please get it examined and get it extracted.
Meanwhile do warm saline rinses ,upon your dentist advise you can start with antibiotics and analgesics.
This will reduce the infection there.
Hope it helps.
Thanks.
Take care.