Self doubts mainly refers to the condition when we doubt our own worth. It can happen with anyone and at any stage of their life.
Self doubts are because of lack of confidence in oneself, lack of faith, attitude to see negative aspects first rather than the positive one.
Overcoming this situation is not a big deal. You just have to do one thing first that's to start believe in yourself. When you start believing in yourself then all your self doubts will automatically vanish away. And if you want to know that how to believe in yourself? Then you need to spend some quality time with yourself, away from distractions. Just read some good self help books like power of subconscious mind, think and grow rich and there are so many. But these two, i will recommend you as they helped me alot. And yes, you have to believe in the power of Almighty also. And you have to take up all your failures as lesson and not as regret. You have to take your success as gratitude and not cocksure. Just be humble with each and everyone.
As what we seed today, it will affect our tomorrow.
I hope this will help you. Please let me know in comments.