Hubby finished his 6 week chemoradiotheraphy yesterday.....

Can someone advise/ help please.

As the title says, my hubby finished his chemoradiotheraphy yesterday ( 6 weeks)...he has been doing fairly well,  unfortunately, a little earlier he became flushed, shaky and nauseous, he has gone to bed, so, is this normal, is it anything I should be concerned about?

Thank you

Xxx