Possible allergic reaction to darvocet?

I was taking darvocet for about a year for a back problem. I think I may have been mildly allergic since one morning I noticed my face was slightly swollen on one side and I had some minor redness from the side of my nose to the corner of my mouth. I quit taking the meds as my back had gotten better, but the swelling remained for about two months afterward. Now that the swelling has finally gone down, the skin is loose and I have faint, blotchy irregularities on the surface of my skin where the redness was (rash?). I never went to a doctor for this since I felt it was very minor and that it should clear up eventually, but my face has still not returned to normal after about five months.

I just started to take it for my arms and have noticed that my face also has been itching. I am going to take it a couple more times and stop if this contunues to happen.