I am looking for other personal experiences with diet and body acne.

Background of myself:
I'm a 22 year old male. Currently 175 lbs at 5' 10". I have been into weightlifting for about 4 years now. My main goal has been to gain weight. I keep supplementation simple. Protein powder, multivitamin, and fish oil. For some periods of the year I get more into my training and diet than others. This spring I added creatine monohydrate to my supplementation (5g/day). Along with this i increased my egg consumption to 6-10 eggs per day. I also increased my milk consumption as well. Now these were the ONLY changes i made. Within a few weeks my back started to break out badly. I don't mean small pimples that you can pop, I mean the large sores under the skin that last days and usually never produce a white head. this lasted for about a month before i became skeptical of my increased egg, and milk consumption and addition of creatine. Therefore I quit all of these at once, and within about a week or two my back acne faded away. Unfortunately, I did not try to cut just a single variable at a time from my diet as my back acne was getting very bad and i didnt have the time to play guessing games.

Now that the fall/winter months are coming back, i am back to the same diet i used before. and the same back acne is reoccurring! I am not exactly sure which source is to blame (eggs, creatine, or milk). But i do not want to discontinue any of them as i am making gains in strength and size. But if i can single out one of them as the source I would be happy to remove it from my diet.

Many people will say it has nothing to do with diet or creatine, but i know for a fact that there is a pattern here for me. So here i am looking for your personal experiences. Has anyone else had the same issues? What did you find that caused your back acne?