Tests are to be carried out on a man who died while suffering from measles with a post-mortem examination due mid week.
Gareth Colfer-Williams, 25, died on Thursday at his home in Swansea, the city at the centre of an epidemic of the disease.
Angela Colfer said her son saw an out-of-hours GP on Wednesday with a rash "from head to foot" but not his arms.
Meanwhile vaccinations will be extended to schools in mid and west Wales.
As the inquiry into Mr Colfer-Williams's death at his flat in Port Tennant continues, Mrs Colfer said her son had recently been treated at Morriston Hospital in Swansea for asthma.
A few days after he was discharged he became unwell and developed a rash.
Mrs Colfer said her son went to see an out-of-hours GP on Wednesday evening with a rash "from head to foot" but not on his arms.
The following morning, Mr Colfer-Williams was found dead at his flat.
Mrs Colfer talked about how her son's fiancee Cairo had told their daughter Dakota her father was dead.
"She just said that daddy had had to go away and had gone to heaven. Dakota started crying," she said.
"She doesn't understand. She's only three but she's very intelligent. She's realised something is not right.
"It's been awful. We're all trying to be very upbeat with her."
Mrs Colfer said her son, who weighed just 8st at 6ft 1in tall, suffered from asthma and was taking vitamins.
His sister Georgia Colfer said: "He was all red. He was covered. He looked like he'd been in the sun for days and that was just before he died.
"I saw him on the days before he died. I was shocked to see my brother so out of it."
His mother said: "He was very, very devoted to family. He did everything with his daughter Dakota."
Health officials confirmed he had been diagnosed with measles but further tests are taking place to determine the cause of his death.
A health board spokeswoman said: "If he had been admitted to hospital with measles or suspected measles he would have been notified to Public Health Wales.
"They had no notification of him."
Dr Marion Lyons, director of health protection at Public Health Wales, said: "Whatever the cause of death in this case we should not be surprised if, as the outbreak grows, we start to see deaths in Wales."
With measles cases in the Swansea area exceeding 800, Abertawe Bro Morgannwg University Health Board said it was continuing its vaccination programme in schools.
Ten schools in the Swansea and Neath Port Talbot areas will offer MMR jabs to 1,700 pupils.
Dr Sara Hayes, the health board's director of public health, urged parents of unvaccinated pupils to take advantage of the school clinics.
She said: "Children and teenagers who are not protected with MMR have a very high risk of catching measles.
"MMR is a simple and safe jab which will protect them during this serious measles outbreak. I would urge parents of unvaccinated or under-vaccinated children to sign the consent form so our nurses can give them an MMR jab in school."
Since the outbreak began in November, 77 people have needed hospital treatment for the illness.
For the third weekend in a row vaccination clinics were held across south Wales in a bid to stem the outbreak.
Meanwhile the Hywel Dda health board serving mid and west Wales has announced plans to offer MMR jabs to all children and young people at secondary schools in Carmarthenshire, Ceredigion and Pembrokeshire from next Monday.
It will also hold drop-in sessions at the Elizabeth Williams Clinic, Llanelli, on Saturday.