I'm a pretty skinny guy, I weight 135 lbs and I'm 5' 8" but I can't seem to get rid of armpit fat (baby fat?). I exercise a lot too! Any suggestions?

Cardio Mix. If you have adipose tissue to lose (not everyone does), then consider an increase in cardio and a balanced diet. However, do not always do the same exercise or you will increase your risks for stress injuries. Mix things up with walking, running, biking, swimming, or circuit training. Ultimately you need to burn more than you consume.
Sorry! . Do back and back exercise to stretch the fat deposits. You cannot lose fat selectively. To do so, you must lose fat everywhere! period!