My husband had a stem cell transplant three years ago as part of his first line treatment for myeloma. Off the top of my head, a few things that might be handy to know:
If they offer your dad ice lollies to suck whilst having the chemo infusion, try plain ice cubes instead. Much less sickly. Also, be prepared to never want to smell sweetcorn again. Something to do with the liquid the stem cells are frozen in, but people who have had a transplant smell of it too for a day or so. It’s very odd.
My H struggled to swallow/eat/drink due to mucosiitis, so I brought him
yogurts (not live/probiotic) and jelly to try and eat. He didn’t manage much in the early days, but the hospital gave him Ensure meal replacement drinks which he tried to sip and managed to get some nutrients.
It’s probably different for everyone, but he didn’t really feel much like reading or doing puzzle books as he had done earlier in his treatment. He just tried to sleep as much as possible. However, it might be nice to have some things to keep him occupied just in case he feels up to it.
Changes of PJs and bed socks in soft fabrics were nice too, especially as he found his skin was very sensitive even months afterwards.
The worst of the sickness lasted about 10 days, then he was able to come home and was much more comfortable recuperating in his own space. He was back at work in a new job about 12 weeks later.
Good luck to your Dad, and remember that although it’s not nice to go through (or watch from the sidelines), the side effects are usually short term. Fingers crossed for a good response and remission for him.