This may be because the contact lens needs cleaning or because it is a different parameter to your original eye requirements. To clean your contact lens, simply wash your hands and dry them, place some liquid solution on your palm and place the contact lens within the liquid solution. Carefully with your index finger rub the contact lens against your palm. Rinse the lens once more with contact lens solution and now the contact lens is ready to be worn.
If you are still having issues make an appointment to see your optician or Eye Dr for a contact lens fitting and eye check, they will be able to help and advise.