Cat behaviors don't just suddenly change for no reason. As for the acting like a psycho, that could be just your cat, or it could be a sign of other issues (most cats will suddenly just dart around the room, jump up to chase imaginary bugs and then be normal again). The new scratcing behavior however could be a sign that something is up with your kitty. Any new big changes in the house (even just rearranging a room or no longer allowing the cat access to a room can cause behavior changes), changes to its diet, changes in the family, changes in food?
For now, when the cat does unwanted behavior, using a spray bottle of water usually helps. You an also redirect. When it starts to scratch where it shouldn't, pick it up and put it down right in front of the scratching post. YOu may just have to "show" your cat where to scratch and where not to. You can use other forms of deterrent, that may be inconvenient and annoying, but work. Block the cats way to what they want to scratch. If its a piece of furniature, place the scratching post in front of the corner(s) they go for. We cover our couch arms with decorative throw blankets, so the cat won't scratch, and its worked. We've also used pillows, and other things to block.
