Suggest Treatment For Swelling In Lips And Cheek

Hi, 3 days ago I woke up to find the bottom of my left cheek and lip were swollen, it appeared to be mostly on the inside of my mouth and was a little sore. Over the course of the next 24 hours the swelling went down and the next day was fine. Now, today I have woke up to find that the same thing has happened on the right side of my face, this time the swelling is a little worse. I have put ice on it, but if anything this seems to make it worse! I have also taken antihistamine tablets thinking that it may be an allergic reaction but this does not seem to have helped ether. Do you know what may be causing this and what I should do?