Well, rule of thumb start with the most obvious problem first; check roots. It might not look like you're over watering, depending on your environment, the centre of the potting mix(what is it in bwt, realised I forgot to ask that very important question) may be staying wet longer than you realise, thus rotting the middle roots. If that's not the problem then the next is under watering or not enough humidity. It's chance of some type of fungus or pest attacking it from inside the pot, but that may not be the case if the leaves that are left look good and the p-bulbs are just shrunken and not discoloured. Some bacteria take hold out of the blue and move fast, killing a plant in no time then can spread to others. There is no harm in checking what's going on in the pot, at least you know what it isn't. As for what you find on line it is all subjective to where you are located, where you have the plants growing (indoors/outdoors/greenhouse/shade house). What it's potted in, that includes the media and pot or no pot at all. If the root are getting enough air flow to dry them out and sunlight. How is the humidity in your region? There are 3 Barbadians on this forum and we live in different areas of this 166square mile island and we have very different kinds of growing set ups to give our orchids the things they need to grow cause of very different humidity levels.