cleansing product to help skin?

So I've been lurking these forums for a few months now, and I'm finally ready to do a cleanse. From what I've been reading, it sounds like I have to start with a bowel cleanse, and I'm wondering which one to try. I'm hoping some kind soul will read this ridiculously long post and offer some advice.

Just to give some background, here's where I'm coming from (sorry this is so long, but I want to give as full of a picture as I can): grew up on a rather poor diet (very few fruits and veggies, lots of processed stuff); started having migraines at age 7. Since then, I've taken tons of over-the-counter pain relievers to keep them at bay - excedrin probably the most. Have also been on tons of prescriptions for them throughout my life, and was usually constipated growing up. Also had mild issues with sebhorreic dermatitis off and on that could USUALLY be kept in check with a prescription shampoo. I am now 31, and have been slowly changing my lifestyle for the past 5 years (changing diet, taking supplements, and exercising regularly - constipation is much better but still an occasional issue). I am also trying desperately to get off all prescriptions drugs, although I still need an imitrex once or twice a month for the migraines I get with my cycle (when my mom died of estrogen-related breast cancer, I took some tests and found that I am also estrogen-dominant, which I'm working to change). Overall, I've felt much better over the past few years as I've made these changes - EXCEPT for one thing. My seb. dermatitis has gone CRAZY since I was pregnant with my son in 2004-2005. At the time, my derm. gave me a few diff. shampoos to try (salex and loprox) and the usual steroid for flare-ups (luxiq). Problem is, my face got so bad I had to use the luxiq ALL THE TIME. After using it for over a year, I stopped cold turkey about 2 months ago (scared by the long-term steroid usage) and the derm. is naturally worse than EVER. I am still using the loprox shampoo, although I would like to get off that as I have no idea what the long-term effects are of that and I'm not even sure it's doing anything. Oh yeah, I never had allergies as a kid, but have developed mild seasonal ones over the last decade...and moving to a very dry climate here in Colorado 5 years ago is also part of my skin problems, I'm sure.

Anyway, I am scared to death to start this crazy cleansing stuff, but know that it must be done. Even if it doesn't help my skin issues (although I'm praying that it will), I'm sure my body needs it after years of constipation and eating drugs. I have been researching the various cleanse products and am completely overwhelmed. I know that I want something fairly easy for my first attempt - 2 weeks or less would be great - and preferably with little or no fasting. No cramping would also be nice. Is there any product that will do this and also address some parasites or candida, or are they all separate products? I suspect I may have either or both issues. I am also extremely concerned about my liver, with all the pain-relievers I've taken in my lifetime, so is there any supplement I should take for that while doing all this? Milk thistle? Or is it pointless, because it will get flushed out anyway?

Thank you so much for your time to read this, and I'd appreciate any suggestions you can throw my way!