vmcd, so sorry you are suffering, I had exactly the same thing happened to me. I had a thrombosed hemmorhoids twice and had the blood clot cut out in A&E both times. I agree with missP it wasnt nearly as painful as it sounds and provided instant relief. Go get checked!!!! (I also cried the first time I saw them in the mirror too, over it now though!)
DS is two now and I still live with flare ups, have read loads, tried loads of things and recommend the following:
DONT eat very high fibre foods. Midwives and nutritionists will tell you to stuff yourself full of fibre, fruit and veggies (natural fibres) are OK, but DONT eat branflakes, Ryvita etc (manufactured fibres), they are very very rough on your delicate system (there is a book called Fibre Menace that explains this more)
For immediate relief of symptoms (but not a cure) put aloe vera gel on your bum. You can find it in the sun tan cream section, works even better if you put the bottle in the fridge first. Apply as often as you like.
Every time you go to the loo, put your feet up on a small stool so you are in a squatting position.Toddler steps work great, and dont look out of place in your bathroom! (look away now if you dont want TMI) This helps fully empty your bowels, and also means you dont need to push so hard.
Preventing things getting worse with your diet is absolutely the most important thing now. Try and identify what makes you constipated and avoid it! (TMI again!) Kidney beans/black beans are good for making your poo soft and therefore easy to pass.
Add a bit of apple cider vinegar to your food, its has lots of good stuff in it that aids digestion.
After baby is born (not allowed to while pregnant still) take Horsechestnut and Butchers broom vitamin supplements, this helps strengthen your veins, helps with varicous veins on your legs too, so you get double benefit!
There all done, sorry for the gory bits! Hope you feel better soon.