Hi TheOddity,
I've written on this topic recently. www.mumsnet.com/Talk/childbirth/2496362-Piles-Lovely
Please note that difene is CONTRAINDICATED in third trimester of pregnancy. Please speak to your pharmacist or doctor before taking it. You can take movicol with no problems in pregnancy, and it's vital to keep your bowels movements very soft to avoid worsening the problem. Plenty of water, lots of vegetables and gentle exercise is usually recommended as the best prevention of constipation, however when you already have piles, it's very difficult to exercise and we need to be more strategic.
Swimming is an exercise that you can do that doesn't put pressure on the piles, and being in the water can help with out her pregnancy discomforts. Lying in the lateral position with the affected side up can bring some relief, as can lying on your front, if you can still tolerate this position.
You shouodnt use any crema for ponger than a week. If the hemorrhoid is still rock hard and pain full to touch after a full week of tropical treatment, and you can not replace it manually, then you might benefit from having a small procedure to remove the clot.
They do get better, and if treated now they will not affect your birth. However, they may worsen after birth (but there are more treatment options for pain control then), and they will probably recurr in future pregnancies.
Good luck. Let us know how it progresses, it's a VERY common problem.