There is a job in "play therapy". It is a certificate program for licensed counselors. You can google to find out which schools offer the certificate, but you would have to have at least a bachelor's degree in counseling (psychology) to start.

At the age of 15 you cant work outside because its illegal and no one will give you chance to work.

http://www.workathomenoscams.com/work-fr¦

Use the link may you will get online job related to your requirement many companies are providing option to work from home and earn money. You can do this you will be able to share your idea and also you will earn money.

I think you should speak with the pastor or some members of your church (or a local church near you) and ask them for advice. They may be able to lead you toward some special youth services that they provide.

There are pastors in the hospital. Definitely you can try to be in ministry (if that is what you have decided), and then head on to children's cancer institute. But since you are young and many youngsters keep changing or unsure, atleast try out different things, till you finish high school, so you can confirm then what you want to do.

Ask the school counsellor, mentors and college counsellors for various fields and your pastor as well.

As someone above mentioned psychology is also good, these days they have energy healers( reiki, energy medicine etc. ) and spiritualists who work closely with doctors.

Is there a children's hospital near you? you could volunteer to help. You could read to children, play board games, sit with a child while the parents go eat or take time for a shower. Volunteering will let you see if this is a job you'd really like plus give you great experience that could lead to a paid position in the future.