It is entirely possible that you had a bug bite or something like that on your face that caused itching. The swelling might be just an allergic reaction, in which case if it is mild the swelling will generally resolve on its own relatively quickly. However if the swelling continues to progress, and spread along your face it may be a more severe allergic reaction. In this case if your vision changes at all, if your speech gets altered, if it gets difficult to breath, or if your tongue/mouth get swollen, then I would say go directly to the emergency room. Otherwise if the swelling seems to be slowly progressing along your face and is particularly red and warm (and if you develop fevers), then it may actually be a cellulitis (infection of the tissue) that is spreading. Either a general practitioner, or a dermatologist
would be able to diagnose any of these scenarios (and there are many other possibilities), but I would recommend starting with your general practitioner. They will refer you on if it is something that they are not comfortable with. Best of luck.