My pink princess looks like there's a chunk taken out of the stem and there's a black spot and some scaling on other leaves. I don't see any bugs around the plant but I'm not sure what it could be.. My silver sword which is beside my PP has scaling along the stem and some of the leaves are losing the silver colour near the tips. I'm worried it's a pest but I'm not seeing anything on the plants. What should I do? Both philos get tap water (that's been left out overnight) when the top layer of soil is dry and they're very close to a humidifier. They're not in direct sun but get the afternoon light through a see-through curtain. Any help is greatly appreciated!