What Causes Atopic Dermatitis While On Loestrin 24?

I have problems with atopic dermatitis for almost 2 years now due to chemical allergies. The worst week of the month for me was the week before my cycle and the best was the week of my cycle. I started on ortho tri cyclen lo in Sept '10 and did well with it but changed to loestrin 24 3 weeks ago due to the cost or tri cyclen. My skin definitely doesn't look as well and I would say I'm having a minor flare up. Trying to decide whether to stick it out on loestrin or switch back. I am a RN and I've been trying to research the different types of progesterone in each pill. Any advice?