Exposure therapy. Should i do for this?

Holi phobia since childhood.phobia is due to colors or that kind of atmosphere really don't know i just know that i  just hate that festival for no reason.i never want to play holi but only want to remain calm at that time.i had actually left so many exams since my childhood but now being a medical student it now is really becoming very difficult  for me.i want to come out of it.after thinking a lot i went for the exposure therapy .during that session i really have not found anything useful in that session.i already know that my fear IS irrational but can't help myself.she during the session asked me to touch the colors and i came out.but yess i atleast was sitting with the colors around me is a great achievement for me but she told me latter that if i would not touch the colors she would not take my other sessions. help please ...what should i do for this