Coping after chemo

Hi all im new here and hope you an help My husband was diagnosed 3 yrs ago with NHL hi grade aggressive stage 4. hes been in remission for 18 months but the side effects have knocked him for six. He is in constant stomack/back pain snd exhausted.  His quality time is between 3 and 6 in the afternoon then hes worn out again. Nothing seems to alleviate the pain. Is this common after treatment and what if anything could help him. We have an appointment  with the oncologist in a couple of weeks. Thanks