I’m very happy because I have completed my first 10 orders on Fiverr with an average good review!
But I have a problem, That I want to ask you
When I have finished my first order on Fiverr, I got many impression and clicks on Fiverr,
Later it has down, and I try Facebook and got orders!.
I got the 5-star review for each order but nothing improving on gig ranking,
I use SEO as well, I don’t what is the problem, I’m on the last page.
anyone have any idea about that.
It may be that the average of your ten reviews is 4.6. Even though your last 3 reviews were 5 stars, you have one that is a 2.3 
Plus because reviews can be purchased from some FB sites when some buyers see three 5 star ratings in a row, it can be a red flag that your reviews are genuine even if they are.
For me only one negative review,
Last three order was from same buyer,
But it 100% legal .
He love my first work very much and he interested in my service, I have also an order in queue with that same buyer
That is good. I am happy that a buyer found you that is happy. I merely wanted to point out that as a buyer it can be a red flag and a reason not to order from a seller.
That being said, I see that buyer let you put his last order image in your portfolio it is very nice. 
This article may be helpful to you.
Thank you for your help😊