first thing i would do, if you haven't, is get an MRI. you want to know exactly the nature of your injury. from there, if you haven't torn anything, it's going to take patience and figuring out what works for you. my right shoulder can be problematic due to bursitis. one year, i was unable to do any pressing movements for about 4 months. belive me, i know your pain. barbell work is probably not going to be your best option. dumbells may. you will have to start light. barbell keeps you in more of a fixed motion, where at dumbells will allow you to poistion your wrists into the most comfortable angle. many machines may also be hard because of their fixed plain of motion, but you dont have to stable them like you will DBs. i found the best machine for me was the free motion cable press machine. it is easy to control and keep stable. 

sorry i dont have a better, more specific answer, but if you take your time and try these didnt options out, going light, your body will quickly tell you what works and what isnt working. if you are getting pain, be sure to ice for 20 min right after training. further, i would ice 3 times a day if it becomes at all painful. when training, be sure to leave your ego at home and don't judge yourself by the weight you're using. make the most of lighter weights. squeeze. if you can use the pec deck without pain on chest day, pre fatigue the pecs before moving into presses. that way, less weight will become more effective.