Hi Sencho1999
Sorry to hear about your symptoms.
Usually - the prog cream that is available off the shelf is so weak that it is unlikely to have any effect on your cycle at all, nor on the hormonal fluctuations of your cycle which are very pronounced during peri-menopause. However you could be allergic to the excipients ( what the prog is mixed with) - which is a separate issue from your other symptoms. If you've got it from a compounding pharmacy then it's impossible to stay as these preparations are not standardised and it's difficult to know how much you could be getting.
The spotting is most likely to be due to the peri-menopause - as is the nausea - a common symptom. Some gynaes consider that for women of your age, using the Combined contraceptive pill will help to regulate your cycle as well as providing contraception. If you get on with progesterone normally you might find this works for you. There are a couple that contain the same oestrogen as in HRT - ie estradiol, rather than thre stronger synthetic ones ( you might have used previously?) - called QLAIRA and ZOELY. Qlaira only has two tablet free days and all the other days have at least 1 mg of oestrogen. Low oestrogen is thought to be the main component of PMS - giving rise to low mood and often headaches. Also headaches in peri-menopause are usually also due to the extreme surges and falls in both oestrogen and progesterone.
When you were pregnant - you also had constant high levels of oestrogen and the levels of both hormones increased throughout the pregnancy - hence the disappearance of your headaches.
Here is an article about peri-menopause which might be helpful:
https://www.menopausematters.co.uk/magazine/pdf/Article%20-%20Perils%20of%20the%20Perimenopause.pdfRead as much as you can - and have a think about stabilising your cycle with the CCP as you are still young enough to take it.
As always - if you are worried (about the spotting for example) then do consult your doctor for a proper investigation.
Hope this helps
Hurdity x