At What Age Does A Human Skull Stop Growing?
Possible
Detailed Answer:
I read your question carefully and I understand your concern.
While in the past it was thought that, human skull stopped growing after the age of 20, later studies have shown that not to be completely true. Some changes continue to occur throughout a person's life. It is not so much growth rather than changes in shape and thickness. It is thought that the forehead protrudes forward while lower skull structures move backwards. So that along with changes of thickness in certain areas may lead to the enlargement impression.
However that should be a very slow imperceptible process, over decades, not something you can notice in a couple of years as you say. So other possibilities should be investigated, in particular the possibility of hormonal alterations, like overproduction of growth hormone in a condition called acromegaly. For that reason if you're sure that your skull has changed in such a short period of time you should visit your doctor to check for other signs and some possible hormonal tests.
I remain at your disposal for other questions.