If your new numbers are correct and you are using the prescribed power lens
, there is still a chance that it takes few days for your eyes to adapt to the new correction. It causes a mild blurring and headache as mentioned by you. There is no cause of concern if this happens for a few days.
For your second question, after 18 years it is rare that the power increases but you said that the power in the eyes increased since one year which is not very common and I suggest you see an ophthalmologist immediately to rule out other causes.You may undergo LASIK surgery if you are found to be fit by preliminary tests conducted by the ophthalmologist. However, LASIK is not advised if you have change of power within the past year