Help Save my son.

Hello, I was hoping that you all might be able to save my pride and joy.

I've had this plant since 2018 and at the end of December my plant began to look a little sad, I was worried about root rot so in January I decided to re pot (something I do about one every 1 or two years due to its rate of growth.)

I discovered no root rot but did notice that the roots had blocked the drainage leading to a bit of over watering. No problem I widened the holes and repotted with a chunkier mix of mostly orchid bark medium mixed with house plant mix and added clay balls at the bottom of the pot to improve drainage.

I was anticipating root shock, but it's gone from bad to worse since then. As you can see from the pictures. I've lost allot of leaves. This plant is three main stems in one pot as I've never had the courage to untangle them from one another.

CAN ANYONE HELP, I'm very worried I may loose my pride and joy.

I have recently added lights as I live in scotland and have a north facing flat. (The pot you can see is a cover pot over a smaller pot which has been raised up)

TLDR) My baby is dying after a report. Can it be saved ?