Oh dear! 10 year old make-up could definitely have been making your pimples worse, especially if it wasn't water-based. I keep mine too long (1-2yrs) because I hardly use it, and get breakouts from it. I just bought some new stuff and washed my brushes in shampoo. They really should put expiration dates on that stuff. I think you will have better luck with the new one, if only because it's new