Unexplained nausea

My mum was diagnosed with lung cancer with brain mets in may 2018,  as of Feb she has no active cancer in the body after surgery in 2018 and no new tumours in the brain since jan 2019 after stereotactic radiotherapy, although she has some necrosis

she has been taking steroids, Keppra and diabetes medication
she has recently been weaning herself off steroids and diabetes meds but is having daily nausea and ankle pain which she thought was the diabetes meds but it’s been 6 weeks and it isn’t going

she had a ct scan at the end of Feb which showed nothing concerning and recent bloods have come back normal but still she is nauseas, I’m concerned it could be further cancer

her team have bought her next scan forward from may/jun but we don’t know when, can anyone give any experiences until we can see her team, particularly scary time, especially during a pandemic, when going to hospital poses it’s own risks, even in relatively safe Dorset area 

thank you x

ps I realise no one can provide  absolute answers just some ideas would be helpful, I like to have as much info as possible good and bad x