I had surgery two weeks ago (hysterectomy). I woke up with a swollen lip. At first I thought it was from the breathing tube, then I saw white puss inside my lip and realized it must be a cold sore. I ve been taking acyclovir for two weeks now (morning and night) and I still have a small hard bump inside my lip. The white puss is gone, but when the acyclovir has worn off my lip itches. I ve always had cold sores, but this one was by far the largest one I have ever had. Why would surgery bring it on that fast? Should I be worried?