A week ago i think i was having sinusitis and i felt a pulsating vein in the side of my head near the temple, since then this area became swollen and stiff, its not really visible but i can feel, it also doesnt hurt, what can it be? is it emergent?

Without an examination its not possible to understand what exactly you are describing. That pulsating vessel is likely your temporal artery. It is normal to palpate a pulse in that area. Did you have a sinus infection or was it a cold, allergy, or some other viral illness? 22-year-olds begin to notice bodily functions and anatomy they never paid attention to as a child. See a doctor for an exam.