Hi there everyone! Thanks for your help!
My response rate was going down automatically though I replied promptly every time. So, I was worried cause I had no idea why it was happening, then from the Fiverr forum, I got to know from others who faced same kind of problem and their response rate issues were solved via contacting Customer Support at Fiverr. Today again my response rate went down again and this time I contacted CS and they quickly solved my issue. So, those facing the same sort of issues can contact CS without hesitation.
Here is my gig link https://www.fiverr.com/share/kLLe9y
Thanks, everyone for helping me!!