Why Are My Lips Swollen With Small White Blisters On The Outline?

My lips have been dry and chapped for about a wk and a half. A few days ago I started getting little white bumps around the outline of my lips and the last two nights when I wake up in the morning my top lip os swollen. Yesterday I took one dose of benadryl and the swelling went away for the rest of the day. I took some before bed last night and my lips are still swollen this morning but not as bad as yesterday. I have been using chap stick, aquaphore, neosporin...nothing is helping. Can you tell me what is possibly causing this?