So what do you do about it?

The tricky part about acne is that the problem can actually become worse if you overmedicate. That's because acne medication can overdry the skin, causing a boost in your skin's Sebum (oil) production. This results in…you guessed it – more acne.

So what's the long term solution? Find gentler solutions or even natural acne cures that won't shock your body into more breakouts. Here's what I recommend:

- Use a glycerin based facewash. Glycerin is gentler and will balance the ph levels in your skin.

- For body acne, try using an antibacterial soap to slowly dry out the skin. If your skin gets too dry, switch to a moisterizing soap like Dove to counterbalance the effect.
- Wash your face only 2 times a day max and gently pat dry with a towel.

- Use a gentle face moisterizer if the glycerin based face wash drys you out too much.

- Eat almonds, fiber, drink lots of water and avoid excess sugar intake.

- If acne medication isn't working or causing new breakouts, try applying egg whites to the pimples at night before bed. This natural remedy works great.

- One of my favorite natural skin conditioners is wearing an "oatmeal mask". The oatmeal with smooth your skin while simultaneously absorb toxins and oils from your pores.

- You may hear some people say that toothpaste is a natural acne remedy. It's true that this can work. However, it's really the alcohol in some toothpastes that make the pimples go away. You're better off foregoing the toothpaste and simply apply a dab of rubbing alcohol on a pimple after you pop it. The rubbing alcohol will kill bacteria and prevent further infection.

- Rubbing lemon juice on a pimple will also make it go away. The acidity of the lemon will dry out the clogged pore and balance the ph levels in your skin.

For more great remedies, check out the Source link Below.

Best of Luck!
References :
http://www.Natural-Acne-Control.com

But it sounds to me like you're getting heat rash because the pimples appear so suddenly. Here's some symptoms:
http://www.webmd.com/skin-problems-and-treatments/understanding-heat-rash-basics

What we used to do for heat rash is slather on Noxzema all over our bodies. It brought down the heat and helped clear out the rash as well as clean off the dirt.
References :
experience

too much sun can also dry your skin out, skin will produce more oil than needed, and zits form.

but humidity and temperature might affect it.
References :
MEEZ