Your phone is still damaged as the "expert" you used to replace the screen did not fully repair it. Was this repair done by Apple or an Apple Authorized Service Provider? If not, you will need to take it back to whomever you worked with to see if they can rectify the issue.
Unless you use a qualified technician to look at your phone, you may never get the answer. There's no way anyone here can diagnose the issue for your phone to tell you exactly why. The damage from the fall apparently caused more issues than just the cracked screen.
Most likely the problem wasn't the screen. As Apple didn't repair it they will no longer touch it to find the actual cause of your problem. So you are completely on your own.
Yes I haven’t repair it from the apple, but how can it be stated on the exact same spot, the position could be changed if he hasn’t repaired the screen properly, even after putting an other screen.
there are rainbow lines on my screen even after I changed the screen
