A Glastonbury man is urging people to be persistent in expressing health concerns, after claiming doctors misdiagnosed serious conditions in his family over a seven-year period.

Phil Parker says that in seven years, doctors have missed two cases of deep vein thrombosis (DVT) – suggesting it was 'muscle discomfort' – and mistook diverticulitis – a condition that occurs when the pouches in the wall of the colon become infected and inflamed, causing a constant, severe pain, and fever – for gastric flu.

He also says that a bacterial infection in his daughter's lung, when she was 18 months old, was missed.

He said the mistakes had resulted in a number of meetings with doctors after he raised his concerns, but he still feels that his worries have not been addressed thoroughly.

"I know that doctors are under a lot of pressure, but if we hadn't been persistent, then things could have been very different, particularly with the lung infection my daughter had," he said.

"It was only because we were persistent that Musgrove Hospital agreed to see her – they took one listen to her lungs and said she urgently needed an x-ray.

"They thought she had pneumonia – as it turned out it was a serious bacterial infection – but we'd been told by our doctor to just take her home and bring her back in a few days if there was no improvement."

He also called on the NHS to review its triage system – designed to help medical receptionists determine how urgent a request for an appointment is – saying that it is not appropriate in all cases and could cost lives. "Under the system, I had to fight to see a doctor," he said. "And I had DVT, which can be fatal."

Paul Courtney, a spokesman for NHS Somerset, said: "Patient confidentiality prevents NHS Somerset from commenting upon the care and treatment of any individual patient.

"However, if an NHS patient is concerned about the quality of their health care or the advice they have received from their GP they are always advised to raise their concerns with the doctor at the time of their consultation.

"If they feel unable to do this, they may express their concerns in writing to the practice or seek advice from NHS Somerset's Patient Advice and Liaison Service (PALS)."