It is hard to advise, especially on a forum like this. It could be either or.
From experience...my daughter was vaccinated at age 2 when the pox vaccine was very new. When she was in 5th grade, we had just returned from Hawaii and she went back to school. A day or so later, she had a little rash but it was not itchy, no fever, etc. I assumed it was from the tanning products, etc.
The school nurse called me and informed me that we had exposed the school to chicken pox. I had NO IDEA it was possible to be chicken pox because she had the vaccine.
This is around the time when most kids who were vaccinated, starting having mild cases. We parents did not know our kids could get the pox after a vaccine. Now, a booster is required around age 10 if the child did not have a case of the pox.
Lesson learned for me. It was at that point, I got very turned off to new vaccines. My daughter did have a very mild case but she got the pox even after a vaccination.
Good luck!