What Causes Pain Across Shoulders At Night While On Chemotherapy For Lymphoma?

At about 6pm I start to get a pain across my shoulders then early hours of the morning I have severe pain that keeps me awake most of the night I take pain killers that work after an hour I recently had stents replaced in my kydneys I am also having chemo for lymphoma I am 71yrs old I don t have pain at all during the day only in the evening when I go to bed