Red bump/blister under stitch; ten days after surgery. Any suggestions?

I had Mohs surgery Late June to remove BCC from my upper lip. About five days after the surgery, I had an outbreak of cold sores. I was prescribed Valtrex (2, 2X one day). Now, 5 days later, after the Valtrex, I still have a blister-like bump at the top of my stitches and the stitch is sinking into the bump. I don't have any signs of infection other than the red bump that sometimes feels tingly, and it sometimes feels like a stabbing pain. My face is also itchy, but I wear a retin-A.

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