Tiny Cayson Yale had umbilical granuloma – an overgrowth of tissue during the healing process of the belly button.
His mother Abbey Watson, 21, says she mentioned it to her health visitor, who said it might go on its own – but five weeks later there was still no change.
But when Ms Watson took Cayson for his six-week postnatal check-up at her GP surgery Telford, Shropshire, she claims the doctor treated him with a silver nitrate pen to burn away the excess skin.
Ms Watson says the tot became increasingly distressed as his belly button started to get redder and redder – and she rushed him to hospital, where she claims she was told he had chemical burns from the silver nitrate.
She said: “When Cayson was newborn my health visitor came round, and said he had umbilical granuloma – a small ball of flesh left from where the umbilical cord was attached.
“She said it might go on its own, and I left it for around five weeks, washing it in salt water – but nothing was happening.
“When I took him to the doctors for our six-week postnatal check, I explained to the doctor what the health visitor had said.
“Straight away, she got on the phone and asked for a silver nitrate pen. It was a thick pen with a felt tip end, and she rubbed it all over his belly button for a good minute at least.
“I”m a first-time mum and thought nothing of it – I just thought that was the normal thing to do.”
But after Ms Watson left the doctors, she said Cayson”s belly button started to become red and sore.
She said: “About two to three hours later Cayson”s belly was really red, and I could see it was really sore and gunky.
“I thought maybe that was the reaction it was supposed to have.
“But an hour later it went a grey ash colour and was really inflamed, and then it started getting worse hour by hour.”
Ms Watson rang Shropdoc, a local out-of-hours urgent medical service, who she said saw Cayson and told her to go to the hospital.
She took Cayson to the Princess Royal Hospital, in Telford, where she claims she was initially told her baby had third degree burns, before he was later diagnosed with chemical burns.
Ms Watson said: “Straight away they said it was bad.
“They sent me to a paediatrician at the Princess Royal, and a doctor there told me it was third degree burns.
“I was shocked and absolutely disgusted – you put your trust in the doctors to do the right thing, you don”t expect your baby to come out of a simple procedure with burns.
“I was later told that the correct way to use silver nitrate is by putting Vaseline over the infected area first so it doesn”t touch the skin, and by using a tiny drop on the end of a cotton bud to dab it on – not by just rubbing it straight on.”
Ms Watson and Cayson spent the evening in hospital as medics treated his wounds, and nearly a week later he is starting to recover.
She has now made a formal complaint.
She said: “At first Cayson was very distressed, he knows something is wrong and his belly was painful.
“But luckily it hasn”t affected him too much, he”s a very bubbly baby and he”s still smiling.
“The burns are starting to heal now, but it seems like his belly button has closed up and is healing together, so we might have to get it cut open later.
“I”m absolutely furious, and I feel guilty – I took him to that surgery and let the doctor treat him, and this happened – I”m supposed to be there to protect him and I couldn”t.
“I”m a first-time mum and you just don”t think something like this could happen to your baby – Cayson is my first baby and I was none the wiser.
“I”d hate for this to happen to someone else”s baby too.”
A spokesperson for the Telford and Wrekin Clinical Commissioning Group (CCG) said: “The CCG are aware that an complaint has been made and this is being investigated by the practice with oversight from the CCG and NHS England.”