I bought this monstera with 3 leaves from propagation. When I got it, it was in a temporary pot with just perlite. I then went to a nursery to get it repotted, but they made the soil mixture too dense. I also put it in a cabinet terrarium with grow light, small fan and kept it at 70% humidity. 

After a week though, the plant developed these black spots that are still spreading. I've since move it out of the terrarium for more air flow and repotted it myself a week ago with much more aerated soil mixture of 50% bark, 30% pumice + 20% soil. When I gave the roots a wash, I didn't exactly know how to check for root rot, but there was no smell, and I did give the whole root a rinse and no part was mushy/falling apart + many smaller new roots were forming.  I've also sprayed the whole plant with bonide copper fungicide. Some spots have stopped spreading completely, but the big ones are still getting worse...

One edge of the leaf were turning black with yellow halo, and even cutting into the green section with sanitized scissors, it's still spreading as well... With the new soil and soil tester, I'm also definitely not overwatering the plant anymore.

Is there anything else I can do to keep the balck spots from growing? Would more regular sessions of copper fungicide work? Or if I need to cut the infected spots off, how much should I? Do I need to cut whole leaves off? 😭😭

I'm totally new to monsteras and would really appreciate some help keeping my baby alive and well 🥺

How to deal with spreading brown spots with halo?