Hi AskDocs, I've Had Cold Sores All My Life, And

Hi AskDocs,
I've had cold sores all my life, and while I've been getting outbreaks progressively less and less over the years, their occurrence rate has increased ever since I started going to crowded scenes like clubs/raves/festivals.
I remember the first time in a long time that I had an outbreak was when I went to my first rave. Could it have been from the MDMA that I took lowering my immune system? I did also share drinks with people but I already have the virus so does this even matter? I kind of ruled out MDMA as the culprit after attending a music festival recently where I did not take MDMA but still got a cold sore a few days after. But that was probably due to prolonged sun exposure.
Any ideas as to what's causing my outbreaks and how I could prevent this should I choose to go to another event in the future? Thanks in advance.