So, day 3 was definitely a set back. The sweat did nothing to cause acne - even after letting it dry on from being at the pool & working out the day prior. However, I did get some new acne spots in places where my acne tends to flare up - the most sensitive places on my face. My conclusion is that it was a cause of the sun exposure.
I know this is the case because while I was in the car/out of the sun my skin felt dry and hot - not necessarily from sun burn but just from the exposure on my face. It also makes sense that my skin always clears up really nicely when I spend a lot of time OUT of the sun. Therefore, I am wearing hats for the duration of this caveman experiment. Absolutely no sun on my face - especially because I cannot put sunscreen on right now. Going to buy a new hat this week!
It also makes sense that the sun is part of the reason why I am having issues - when I went to college, I started walking every where. I spent way more time outside in the sun than I ever had in high school - started walking to classes every day, running outside, etc... No more of that! Maybe this is common sense to some people but I never realized that my skin was that sensitive. I will make sure to keep the really sensitive parts of my skin out of the sun from now on - and that includes my face!