I would seek out a new doctor immediately. You CANNOT get pregnant from using a bathroom in which a boy has masturbated. 0% chance. You really have to have intercourse for pregnancy to occur.
I don't know what's wrong with your doctor. She should have done a pregnancy test immediately, which would be negative. Then, she should have scheduled you immediately for additional tests, starting with an ultrasound. You don't diagnose a patient with anything by "feeling" a mass.
There really isn't enough information available for anyone to guess at what the mass is, or if it even exists. Please talk to your parents, as from what you're stating here, you aren't getting proper medical care.
Did your doctor really say these things, Jenna, or are you feeling a mass yourself and wanting to add that part to the conversation?
If you're feeling a mass, and are nauseated, I do recommend you see a doctor, who will perform a pregnancy test.
I just saw the date on this post, over a year ago. I'm sure the poster has figured this all out by now.
It's possible to get pregnant if you put the sperm inside you but it would have to be done within minutes after it came out sperm dies quickly if not in a female do a pregnancy test and see