Seriously instead of all these one ideas here and there, for the hundreth time I'll tell you the truth about pimples.
They are NOT caused by diet (eg. chocolate) , they can be exacerbated by alcohol, stress, hormones (eg. that time of the month), leaving on makeup can cause a pimple.
There is only ONE treatment for the majority of people, Benzoyl Peroxide (sold as Benzac in Australia) 2.5% or 5% are best. Apply once in the morning, once at night to the face. Costs about 50ml@$15. You can also buy Clearasil EXTRA STRENGTH (only extra strength has Benzoyl Peroxide) which is smaller and probably more expensive 20mL@$9.
But yeah, it's exam time, if you're prone to them, it's just going to happen.
Keep beautiful
Keen