Yes you need the pelvic ultrasound to start off, and then perhaps a referral with a view to laparoscopy. Periods are only considered irregular if out by a weeks rather than days. The left side of your abdomen contains the large bowel and a lot of your pain could be from this, but not all. I would al...

I would have a doctor take a look, and see if there is any local lesion as well as any other condition that could lead to referred pain in the area. If no obvious cause is found, this may respond to local injections or a medication taken at night such as amitriptyline.

... I had to go back to remember your last question!
Unexplained is a tough diagnosis but your age and weight are now the important factors so just relax as they're good.

The clinic will probably only repeat the virology, blood groups and semen analysis.
Keep your weight stabel by being sensible, exercise as normal.
It doesn't really matter what time you take the folic acid
and...

To be on the safe side, perhaps your GP could refer you for a blood pregnancy test? If negative, and no periods for 6 months, you will need to be refered for hormone tests.

I would only add that a BMI is misleading, because you need at least 15% of your weight to be fat in order to produce estrogen in enough quantities. Now is a time in your life when you could afford to put a little weight on in a sensible way

To be frank, with your history of perianal complications, I would opt for an elective caesarean section. While most women's tears are small, you are not 'most women'.

Another cause could be recurrent herpes or rarely, allergy to semen.

I have heard a few women say this, that the Iron makes them bleed more or less, and it is hard to explain. I would get an ultrasound of your pelvis as this may discover a cause for your menorrhagia, and there are plenty of treatments available

I agree, and would like to add that thrush is naturally carried in the bowel. It is important to treat your partner, and to use the cream to eradicate it from other sites on the body such as between the buttocks/groin folds/belly button and under your breasts. In case it is not thrush, ask a doctor ...