relapse after 4th round of rchop

My father had his appointment with his oncologist yesterday. It seems that his body is not responding well to the rchop treatment. The two lumps that were found in his armpits and the fever are results of this. But will know for sure when we have results of ct scan which was taken yesterday. It could be that his regimen will be changed to something even more stronger. I'm very worried. Having a relapse after the 4th round of chop doesn't sound very promising. Has anyone gone through this same experience and what kind of regimen was introduced and what were the results. Sorry for asking all these questions, but i feel lost and giving up hope.