Lots of yellow heads appearing on my face, why?

Hi there.

For the past 5 days or so I have noticed yellow heads appearing on my head and also I can feel them on the back of my neck. I haven't changed my diet, still getting around the same amount of sleep. I am in my mid twenties, male and quite healthy and fit.I have noticed that dairy seems to be the cause of my acne however maybe it is a lot of things. There are a few things however which may have contributed to this, maybe all these problems are causing these yellow heads to appear?

-About a week ago I ate a few small apple pies and also a small Kit-Kat. (Both have dairy)

-My pimple cream has gone out of production for 4 months and I haven't used it (Or anything else) for about 2-3 weeks. However I was only using it once or twice a week in the first place.

-I did eat quite a bit of dairy free icecream, maybe sugar is my problem?

-I have recently gained more hours at work in hospitality. I have gone from 4 days to 7 days and have worked the past 15 days of 16. My job involves being around oil, smoke, grease and cooking food on a grill. Could they have got into my forehead?

Please help. 10 points will be given.