When you read without specs when you have such high power it'll cause difficulties in reading and in ability to focus. I would advise you to wear your specs full time especially since you have a high power and it should be used full time. You should get your eyes checked again and see if the power remained constant and to rule out other problems such as astigmatism. If the problem persists or worsens visit the opthalmologist at the earliest.
Next Steps
Follow the steps as advised
Health Tips
If condition persists or worsens visit the opthalmologist at the earliest