If you have faith, it is a way to grow. Discover the source, the reason for your doubt. Talk with others about your feelings...especially those who will listen to your concerns with an open mind.
There have been times when I have had doubts. Truthfully, to me they were scary times, lonely times, times when I was reaching out for God's direction and strength to carry me through times which I found troubling and difficult.
Be still. And wait. God is there...He is. He is carrying you through your time of doubt.