I suggest that you mention this issue to your primary care doctor
. Your doctor will be able to take a look at your head and decide whether or not your head is actually bigger on one side than on the other.
There are some rare causes of an increase in the size of the skull in adults. One of these would be Paget's disease, which is a condition in which bone growth proliferates unchecked. Another would be a tumor growing inside the bone. I think it is unlikely that either of these things is going on without other symptoms, but your doctor will be able to rule them out.
Other possibilities would be that you bumped your head and have a bruise or some swelling in the tissue overlying the skull. A final possibility would be that some of your lymph nodes, located low down at the base of the skull, are swollen from a recent infection.
In summary, I think it is unlikely that what you are feeling is something serious. However, your doctor will be able to check it out and reassure you. If you have any serious symptoms, such as headache
, weakness, or dizziness
, you should mention those to your doctor.