What causing acne and what makes it better really fast? Without any medications. 

Needs medications. Acne occurs when skin glands produce more oil, but the openings of the glands are blocked by little plugs of dead skin cells (comedones). Skin oils leak sideways into the skin, causing inflammation that brings in lots of white blood cells, forming a pustule. Causes include hormonal changes, emotional stress, certain medications, skin rubbing, etc... Only medications can make it better "quickly".
Start with... Over-the counter stuff. (yes, they're medications, but not prescriptions.) get a good acne wash with salicylic acid, and some benzoyl peroxide cream. Use every day, consistently.