Anybody have any additional newborn soothing techniques?

My son is 4wks old. He gets into a lot of crying spells for apparently no reason. I feed him, change his diaper, rinse his pacifier (in case it tastes bad lol), try reading to him, shaking rattles, playing music, bouncing him, put him in a vibrating chair, in a baby carrier, in his swing, I sing to him, swaddle him, hold him close to me, I've tried white noise.. The only thing that seems to work is comfort nursing, he doesn't actually nurse, more like latches on and falls asleep, but as soon as I go to burp him if he did eat anything or lay him in his bassinet, he starts crying again.. Any ideas? Is comfort nursing common for newborns and an ok practice? Does this phase last long? I feel terrible when I can't get him to stop crying. I just want to comfort him. Thanks for any advice!