Do have a little pressure behind my forehead and a little headache. i was also nauseous . do i have a brain aneurysm?

Probably not: Your headache may be related to a tension headache or migraine. Aneurysms tend cause severe, sudden onset pain when they rupture. If your headache continues, consider seeing your doctor who can do a neurological evaluation and decide if a ct or MRI would be helpful to determine the cause of your headache.

Unlikely: These symptoms are unrelated. Most aneurysm cause no symptoms whatsoever, until they rupture. Your description does not fit any aneurysm rupture. Brain aneurysms are quite common and therefore, you may have one. The only way to find out is to get a cerebral angiogram. Again, your symptoms do not suggest that you have an aneurysm and therefore may get the angiogram some day.