Do you expect to run a business with this app ?
If yes, fill a leancanvas (on paper or http://www.leanstack.com/), validate your assumptions with interviews of patients and psychologists, show them mockups of the app with uxpin or balsamiq. When it's validated that you can earn money (how much are they willing to pay, how many are they), outsource the development.
If no, find a student to get the job done or if the app is not very complicated, learn to do it yourself with mobile app builders (http://mashable.com/2013/12/03/build-mobile-apps/).
If you need more advice, feel free to have a free call with me https://clarity.fm/laurentroger/white665or on www.sohelpful.me/laurentroger