This is because the factor-50 sunscreen she carefully applied deprived Tyler of essential vitamin D, which is produced by the body as a reaction to sunlight on the skin.
Rickets blighted Victorian-era Britain but was virtually eradicated after the war as diets improved. Tyler, however, is one of a growing number of children found to have the condition or associated vitamin deficiencies thanks to a tendency to cover up more in the sun.
She was eventually diagnosed in November, after tests to establish why she had failed to recover properly from an unrelated operation on her hip. She suffered constant pain and weakness in her legs. Her vitamin deficiency, which could have developed into the more serious rickets, has been treated by taking a multi-vitamin.
Tyler said her illness left her legs feeling 'really heavy so I couldn't move them'. She added: 'It made my whole body feel really ill and achy.'
Details of Tyler's case emerged a month after health experts urged people to spend up to 15 minutes in the midday sun without sunscreen three times a week to help boost levels of vitamin D.
Around one in 1,000 children are diagnosed with rickets, although figures suggest that as many as 70 per cent have a vitamin D deficiency.
The advice contradicts previous warnings about the dangers of time in the sun when it is at its strongest.
If you'd like to comment on this story, please email the editorial team at: firstname.lastname@example.org