I feel numbness and pressure near my left nostril combined with headache. had a cold a week ago, what could it be? should i be scared? slightly feeling like my left part of the nose is swollen from the inside.

May need a doctor: The nose swelling and headache suggests some infection, such a perhaps a sinus infection. Seeing one's primary care doctor can help. Some people find help using a few days of decongestants and/or antihistamines to open up the sinuses and let them drain; and add some ibuprofen or acetaminophen for aches and pains. One's doctor can examine to see if antibiotics are needed.