Old Separated Shoulder Injury

I'd recommend you see an orthopedic surgeon, one who specializes in athletes (ask the local tri club for names)- many of their athlete cases are not actually surgical but send-the-patient-to-physical-therapy type of case or a sports medicine doctor.  At the very least, they will likely want to take x-rays, and maybe an MRI to see what's going on in there.  You may be sent for PT.  I'm currently going to PT for a recent (minor) shoulder separation injury-others have told me that some of the exercises I'm doing there are going to be ones I am going to have to do at times, when the shoulder acts up again- I guess they keep everything tight.  But first see the doctor so you can know exactly what is going on as there is always a possibility with any injury of there being other related issues down the road.