Getting to the bottom of a breakout can involve a lot of detective work. There are many factors that can contribute...
- What cleanser do you use?
- What shampoo do you use?
- What type of makeup do you use (mineral powder, liquid, brands, etc.)?
- How long did you stop using makeup for?
- Do you use hairspray?
- What kind of foods do you eat?
- What do you drink?
- Do you have allergies?
- Is it humid or dry where you live and work?
Rossie is right, bangs will often make breakouts on the forehead worse, so stepping up your cleansing ritual is advised. Changing your pillowcase often (nightly) is also very helpful.
I would recommend checking your cleanser and makeup against the Beautypedia database
to make sure neither contains something that might be bad for your skin.
A healthy diet is also important, though what constitutes healthy is up for debate. I do think that avocados are very good for you, milk isn't, and lemon and water won't hurt.
Something to remember is that if you make changes, it may be weeks or months before your skin calms down fully, so don't dismiss the effectiveness of something if you don't see immediate results.