Are A/D's appropriate in treating steroid-induced morbid depression in a bipolar Crohn's patient?

Patient is a 67-year-old bipolar male currently suffering acute flare-ups of Crohn's.  Gastroenterologist is treating with Prednisone; however, patient is now experiencing morbid depression - possibly as side effect of the steroids together with ongoing sx's of underlying MDD secondary to chronic pain of Crohn's.  Inasmuch as the patient is also taking other psychotropic meds (e.g., lithium, seroquel) for bipolar, would the addition of an SSRI or SNRI be contraindicated in this case?  How best to help this patient manage the acute depression, albeit iatrogenic, as well as the underlying situational depression secondary to long-standing, poorly managed chronic pain from his Crohn's? Would, say, milnacipran or desvenlafaxine be an appropriate drug to add to this patient's medication regime... what meds might need to be tweaked to help this poor guy get through the worst Crohn's flare-up yet, avoid negative drug interactions and side effects, etc?  Is there a psychopharmacologist in the house?  Pain psychologist?  Psychiatrist?  Sorry for the long post; this is a dear friend and we are very concerned about his mental state.  In my experience, if you can effectively treat the depressive sx's then it becomes much easier to deal with the physical aspects and, while the pain itself might not be going anywhere... the suffering and 'stinkin' thinkin' can be considerably lessened, and cognitive/behavioral therapy become much more effective as a coping strategy.  This guy is one of the sweetest humans on the planet.  Please help, if you can.  Thank you so much!!!