You can find full details on caring for your fiddle-leaf fig plant in our Guide to Fiddle-leaf Fig.

Sorry your Ficus lyrata (Fiddle-leaf fig) is not doing well. Ficus re-potting is best done in spring time and your plant is stressed by having been re-potted too late in the season. Now that the days are shorter there is less duration of light and plants slow down their growth.

Fiddle-leaf fig plants like to be slightly root-bound and can stay in the same pot for several years. When lots of roots appear above the soil line or through the drain hole, move up just one pot size in the spring.  The pot should still seem to be a bit tight. A conventional, soil-based potting mixture with some added perlite for good drainage is best.  Your pot must have a draining hole at its bottom.

Many fig problems start with keeping the plant in a decorative container without a drain hole. You can insert a plastic pot with a drain hole inside of a decorative, non-draining container as long as you remove the interior pot when you water and allow the soil to drain completely before replacing your ficus in the decorative container.

When maximum convenient pot size has been reached, top-dress plants annually (instead of moving to a bigger pot) with fresh potting mixture. Topdressing is just removing a couple inches of potting mixture and replacing with fresh. Looks like you will have to return to the original pot.

Courtesy of the NYBG Plant Information Service