If a stretch is hurting or you can't get into the stretching position, you can first try to modify or alter the position of the stretch and range of motion you are stretching in. You may also want to try the recommendation in the article suggesting shorter hold times and more repetitions of the stretch, which may make it more comfortable. If you have tried the above suggestion and are still experiencing difficulty, and maybe even shoulder pain in general, consult with your medical doctor and they will likely refer you to a rehab specialist for further guidance and recommendations.