Your increasing left-sided headaches could indeed be linked to eye strain from worsening eyesight, as your eye muscles work harder to focus. Additionally, frequently using Crocin (paracetamol) can sometimes lead to 'rebound' or medication-overuse headaches. Other possibilities include migraines, which typically affect one side. I recommend scheduling an eye exam to check your vision. It is also important to track how often you take paracetamol and consult a doctor. They can help safely manage your pain and identify the exact cause to bring you lasting relief.