It is something of a myth that diet is a cause of acne
. There is no definitive evidence that changes in what we eat have any major impact on the development of acne.
The most common causes of acne are either things that increase debris on the surface of the skin, thereby clogging pores, or changes in the body's hormone levels that lead to increased proliferation of bacteria on the skin, also clogging and inflaming pores.
With regard to the first cause, this is commonly brought about by increased physical activity, sweating, etc. If this applies to you, you simply will need to pay more attention to your skin hygiene routine, and things should clear up.
With regard to the second cause, this commonly is brought about by new medications that impact hormone levels, by body building supplements in men, and by polycystic ovarian syndrome in women.
If you are uncertain what might be going on in your case, make an appointment with your primary care doctor
. They will be able to review your current health status and determine whether anything in particular might be provoking this recent problem with acne.
Good luck with this, and I hope it clears up soon!