Hi jedigirl
I just read something on the web about acne and periods so this is relevant to greasy hair I would think - looks like progesterone could be the cause?
http://www.webmd.com/skin-problems-and-treatments/acne/features/periodThese behind-the-scenes hormonal shifts do all sorts of things to a woman's skin. For one, the mid-cycle progesterone rise stimulates the production of sebum. Sebum is a thick, oily substance that acts as a natural skin lubricant.
“And as levels of progesterone increase, skin swells and pores are compressed shut,†explains dermatologist Audrey Kunin, MD, of DERMAdoctor.com. As a result, pores never looked so minimized. “But this tourniquet effect also causes sebum to build up beneath the skin's surface.†.
The reason for your lack of period could well be because you are taking progesterone of most of the month. If your oestrogen levels are also beginning to decline (ie during the peri-menopausal phase) then some months your womb lining won't build up enough - progesterone helps to keep it thin.
I can't explain the feeling sick and dizzy etc - at what stage of the cycle of oestrogen and progesterone did this occur? You may well expect to feel like this for a couple of days after stopping the progesterone ( eg days 27-28) because the progesterone withdrawal causes pmt in many women. However also your own hormones may be doing their own thing ( fluctuating) in the background - which may not help.
Yes, why not try less progesterone as you suggest? If you are going to use it for part of the month then only 12 days max are needed - although if your periods end up becoming heavier again you might want to increase the number of days again temporarily!).
Hope this helps but sorry I can't be more specific - because how your body goes through the menopause and exactly how your own hormones fluctuate, will be unqiye to you - so only general ideas can be suggested.... there won't be a perfect solution but the aim is to feel better overall while riding out the fluctuations....
Hurdity x