I went through interferon treatment at one point for something else and it did not go so well as you describe symptom and reaction-wise, in addition to becoming very weak. I appreciated the friends that reminded me that they were there if I needed anything, including running errands such as to the store or to pick up scripts, etc. I lost my ability to do simple things, everyday things, even cooking and cleaning became major chores and taxing; I just had no energy so they would help me out and felt like such a burden on everyone, that I ended up hiring someone to clean. But if you can, watch where you might be able to help and asking though, only stepping in where he'll let you. Everyone is SO different is in this regard and make not like the help but reinforce you are there for them if you are and where you can be. The treatment will not last forever and is only temporary, something to remember to remind him when things get difficult as it will be hard to see past some days. I know baths are not something many do anymore but especially with the chills and fever, warm/hot baths were a real saving grace during this time instead of showers and you might be able to suggest this. Ginger and peppermint teas helped with nausea as well. Sometimes the hospitals will have support groups with other suggestions, which would be something to look into for ways that can help with the symptoms and for support as well; this might be something to check into as well. There days though that I just wanted to be left alone so have to watch for this as well to balance it; gentle reminders but not hovering especially as a roommate. The fact that you are concerned is nice that he has you as a roommate.

Just be supportive and encouraging, do what you comfortably and reasonably can, and it will be appreciated. Sending good wishes y'alls way and hoping the treatment goes really well.