Been there!!! It is so unbelievably frustrating.. I know you probably don't want to deal with it right now, but here's what we have done and it worked really well.
We had to get a second litter box for our two cats. Turns out, the younger cat (7) was sneaking up on the older cat (9) and ambushing him when he went potty.. So the older one would poop where he could see and feel safe (right outside the litter box). Putting the litter box in two separate places helped the kitties to feel like they had safe places to go.
You have to find all the spots, things, and clothes they've peed on and seriously clean them to remove the pee odor all at the same time. If you leave anything with pee out, they'll pee on it again. The enzyme cleaner (Nature's Miracle or PeePee) works the best and neutralizes the odor. If the bed has been peed on, you're probably (excuse my language) boned because the pee soaks into the mattress and you can't remove it. Once it's marked, they will keep peeing on it. I have a plastic liner on my bed in case this happens. If you can at least soak a bit of enzyme cleaner on it and then use the pheromone spray (mentioned below) that might help tremendously. But definitely get a waterproof liner on it so they can't pee through the mattress anymore if it continues.
Keep all clothes, towels, and non-necessary soft items off the floors completely so the kitties have less things to pee on. This can even include putting up your bathroom and kitchen rugs so they don't have a soft spot to pee on.
Clean the litter boxes at least once every two days for the time you're trying to fix these issues; once one cat marks the litter box, they might want to continue marking other areas until this issue gets worked out.
There is a special spray that has cat pheromones in it to calm them down and keep them from peeing in certain areas. It is expensive, but it really really works. I think it's worth it because our cats stopped peeing under the nook when we used it.
And lastly, patience, of course. The kitties probably sense there is something going on, and they are frustrated too, even though it seems SO unfair that they are doing this to you. If they keep it up even after you've done these things, you *might* need to take them to the vet for a check-up. Kitties can get bladder infections and they will pee and poop everywhere for no apparent reason.
I really hope you can work this out. I know how hard it can be to deal with this kind of thing.. I've had my cats for 10 years and sometimes they get into a funk and I have to totally change things around to accommodate them or it'll just keep happening. I love them so much and I hate how mad I get, but how else are you supposed to feel when your house is covered in crap!!?