Female cat keeps peeing and pooping everywhere?

We have a female that is about one years old now, spayed, declawed, shots, the works. She all of a sudden started peeing and pooping on our clothes, furniture, rugs, anywhere she can find a spot. The worse was the chair and couch it got so down into the crevices it was horrid. Thankfully we have leather but it was still horrible to clean up. I can in fact still smell it. Last night she pooped in the couch on my son's blanket and our clean folded laundry I had yet to put away. Then this morning she peed on the loveseat. What is her deal? I am about to find her a new home. I have three little babies and I cannot have that behavior. I should mention she is a blue point siamese.