If your cat was already checked out by the vet and everything was fine, that's great!
It sounds like your cat is being stressed and he's mad at you for going out of town, that's why he's pooping on your things. He's 'marking' your things, like he wants to 'mark' you, as his own. Even if you haven't left lately, he remembers what he did in the past when you did leave. You should wash/clean all the items he's soiled with an enzymatic cleaner like Nature's Miracle. This is sold in all major pet supply stores and online. Just make sure whatever you get, says 'enzymatic'.
If you don't clean/wash with this type of product, he can still smell where he's gone before, and he'll think these are appropriate places to go again. Nature's Miracle also makes a laundry detergent.
I would recommend trying Feliway plug-in diffuser and/or spray. Feliway is a cat appeasing pheromone which instills a feeling of calm in most cats, and also curbs inappropriate elimination and marking behaviors. You can find Feliway at major pet supply stores like Petsmart, Petco, etc., and also online:
If you use a plug-in in your bedroom and also spray your bed/clothes (it has no scent to humans, only felines can detect it), it should help curb him of this habit.
Another alternative is to lock him out of your bedroom and don't leave your things around for him to poop on. For example, don't leave any clothes, jacket, shoes, backpack, etc., in any other room or on the floor. Put everything away in your room and close the door so he can't get in.
If it's impossible for you to keep him out of your room, just use the Feliway and make sure not to leave anything out on your bed/floor, etc.
You can also try a kitty litter called 'Cat Attract'. It contains herbal attractants that help cats who have strayed, to start using the box again. I realize he's still peeing in there, you only have to get him to also poop in there.
If this problem doesn't subside soon, I'm afraid another vet visit might be necessary and if no medical reason for this is found, your vet might suggest an anti-anxiety medication.
Please keep me posted and I hope you have success with the Feliway! Thanks!