There are a number of things that can cause shoulder pain. I actually have been through a lot with my shoulder, so I would be happy to share. The most common cause of shoulder pain is overuse and tendinitis, from things such as poor ergonomics at the computer or work stations. You can browse the internet for tips on improving the set up of your work stations. I have posted a link from Wikipedia for you to look at about Ergonomics. Tips that I use, for example, I have a roller ball mouse, so I don't have to move my shoulder to move the cursor on the computer- I use my thumb instead.
I was diagnosed with Shoulder Impingement Syndrome in 2008, tendinitis of the shoulder and I also had a type II acromion bone, which is essentially a bone spur of the shoulder bone. In April of 2008, I had shoulder arthroscopic decompression surgery and coracoacromial ligament release, which means they removed part of my ligament. This surgery was done to prevent me from developing a Rotator Cuff tear.
I have been in horrible pain ever since, but I was in a lot of pain before hand, so it's hard to say where I would be if I chosen not to have the surgery. The doctors now are looking into other possible sources of my shoulder pain, like my Fibromyalgia and the fact that I do have some bulging discs in my neck which can cause referred pain in your shoulders and even pain into your hands and fingers.
I would check with your doctor if I were you. See if he/she want to do an MRI. I am not sure what you're daily activities look like, but most likely, you probably have a case of tendinitis or Impingement Syndrome. Most of the time the treatment for it is PT, rest, ICE, and NSAIDs (like Ibuprofen or Aleve) if your stomach can handle them, and sometime steroid injections. For most people this condition will go away with treatment.
I would NOT suggest surgery unless you ABSOLUTELY have to (like if I actually did have a Rotator Cuff tear). If I had to do it over again, I would NOT have the surgery just to remove the bone spur. I now have to take an NSAID to control the inflammation and I sometimes have to ice my shoulder at night even a year and a half after the surgery. Let me know if I can be of any help to you, or if you have any further questions about the topic.
I also have severe shoulder pain, worse in my left than in my right, and fibromyalgia. The pain is from the fibromyalgia. If it continues to bother you, I would ask your doctor to check it to rule out injury. Don't rely on diagnosis on here, as many people do not understand fibromyalgia and all of the associated symptoms.
I have terrible left shoulder pain from fibro. Gets a lot better but still there for a while, then back to terrible. Prayer helps. Good luck and bless you
I have right shoulder pain but mine is due to tendonitis; came from no where and got progressively worse until it hurt so bad to move it up or back i flinched in pain. Doc sent me to physical therapy and that helped immensely. I also have kidney disease stage III so i have to watch what medications i take and nsaids are out. ice on it 3-4 times a day really helps. Wishing youi luck.