Its no longer a root problem. But for future reference, you could completely bareroot it and all would be fine. Succulents are not instant reactors - if something goes wrong, they will let you know in about 3 months. Sort of like turtles (Oops, different subject).
All that you did was perfect: new 'cactus and succulent' soil, new (smaller) pot. Crassula (the Jade plant genus) are famous for developing sooty mold. That's what you have now.
Move your Jade to a SUNNY spot (the small spindly growth is due to lack of sunshine) , wash the mold off and make sure there is good air circulation around the plant. Put it in front of a fan if you need too.
Give it a haircut. You can cut it back as much as you want. But look at it; study it.... and decide where you are taking this plant (or where it's taking you). If it were mine, I would cut every branch back to just 2 or 3 branchlets. I like the openess of your plant but if you want it to be bushy, don't be afraid to prune back further. It will re-branch. It may take a year. Patience. Remember the turtle.
Feel the leaves. When they are soft, water. Drench. Then leave it be until the leaves are soft again. Don't ever let it sit in water.
Daisy
