From your history looks like a case of strabismus . To know the cause , a complete cycloplegic refraction at nearby clinic is a must . Definitive treatment will be a surgery to correct the mis alignment of eyes . Thorough history and previous records needed.

With this photo your squint is not visible at all. But as u r giving a history of squinting. U need to upload previous prescriptions or your eye pics taken while looking in various directions. According to this pic your left eye is looking bigger than right. Please check your old passport size pics taken over the last 10-15 years that whether this was present earlier also or is this a recent finding.