Don't be worried about that , simply concentrate on your work with consistency.
Ranking fluctuation can be happen and it is also a part of blogger life.
It will automatically grow up, when your website will go to improvements side.
When I was started KnowledgeIDea journey then the same thing was also happened to me and I was stuck due to this problem but with the passage of time and with daily activities rank was become better.
You should be optimistic