Hi this is difficult as my husband was the same, stage 4 lung.  In the end I bought a bottle of gaviscon and he took that,  suck peppermint sweets as well and try not to lie flat, prop the pillows up.  Keep off acidic drinks, plain water or warm  lemonade help.  It is part of the problem with radiotherapy especially in the chest area.  Good luck. Carol 

I had this problem during radiotherapy, eventually got some anti nausea medication prescribed after being told that basically I was lying about feeling sick all the time. 

It took the edge off the nausea but didn’t stop it. The feeling gradually faded over a period about eight weeks after radiotherapy finished. 

Thank you for your reply.

With an alteration to her meds and a stash of mints that were the only thing to help me through 2 pregnancies with heartburn, she's a little more comfortable.  I shall stock her up on the lemonade too.

Thanks again