Perhaps give your shoulders a rest for about a month or so an steer clear of any exercises that cause discomfort. For pain id make sure you take flax oil and fish oils iv found personally they have helped with joint pain.
Personally id ditch the decline press for the time being an perhaps learn proper bench pressing technique so as to save your shoulders.
Here is a mini series from dave tate on bench pressing. I highly recommend you watch them as the technique he teaches takes a lot of pressure from your shoulders away
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