Swimmer's Shoulder Concern

My first tri is five days away. About two months ago, I stopped swimming due to shoulder pain. I believe the injury occurred as a result of a few things; 1) from no swimming, to lots of swimming in a short period of time, 2) somewhat poor swimming form and 3) cessation of weightlifting. Prior to the injury, I was able to easily complete the required half mile distance. At rest, the pain is now non-existent. i still feel some pain when maneuvering my arm in a particular position. I previously decided that I would not do any swim training, and make-up the difference by loading up more on the run and bike. I feel confident that I'll still be able to complete the swim on race day. I feel strong and prepared. My question is, am I being over-confident in my belief that I'll still be able to finish the swim? And, has anyone had a similar experience? Thank you.