I received the shingles vaccine 3 weeks ago. A few days afterwards, I had a slight fever, along with redness, swelling, and a rash at the injection site for few days. Pain continued for about 10 days. I felt lethargic and slept a lot during that time. I thought everything was OK now. However, this evening a blister-like thing popped up suddenly in my armpit. It is not itchy, but is sensitive to my clothing rubbing it and is painful when pressure is applied. Could this blister be a delayed side effect of the shingles vaccine?