Also, sterling silver isn't the best thing for a new piercing. Some people can't even wear it in healed piercings, and for something that's still healing, you ought to use good quality stainless steel or titanium really.
Also, stop taking the jewelery in and out so much! If you'd left the original jewelery in, it wouldn't have had the opportunity to "not go throug your nose anymore," would it?
Also, it's red, has green puss, those are both signs of infection. Is it hot to the touch? that's another good sign. Anyway, you could try going to the piercer and asking if they can help you get the not silver jewelery back in (which will help with healing, but won't fix an infection), and you could try going to the doctor about the infection.
Like Brezza said, no matter what the Dr. says, don't take the nose screw out. If there's an infection, you don't want it to get trapped inside your nose, and the jewelery will let it drain.
Good luck!
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I just realized that there's a word for, "bizzare unwarranted affinity" in Casteallano. just one word.