Pain following athroscopic subacromial decompression

I had athroscopic subacromial decompression and resection of AC joint on March 7th - this to correct impingement. 4 weeks later I am still in a lot of pain! The surgeon's report said the bone spur which had developed had pierced a hole the size of a buttonhole through the tendon and that muscle, ligament and tendon had to be cut (?) I have movement OK but with a lot of pain - having to take 2 xco-codamol 30/500 four times daily to ease (not remove) pain. I can't get arm behind my back - physio exercises are very painful - some impossible due to pain. How long should this pain last? I also have a 'click' when I lower arm after raising. Is this normal? Don't go back to see surgeon until 28th April.