A misdiagnosis may support a medical negligence claim if the healthcare professional’s care fell below a reasonable standard and this caused avoidable injury or worsened your condition. You would usually need medical records and an independent medical expert’s opinion to assess both the treatment and the link to your harm. In England and Wales, the usual time limit is three years from the treatment or from when you reasonably became aware of the injury, although exceptions can apply. A solicitor regulated by the SRA can assess the circumstances and explain possible funding options.