Hemorrhoids all of a sudden at 40 weeks :/ ...?

I've had such a great pregnancy, my worst symptom being heartburn. Now all of a sudden over the last week I've become so horribly constipated, which makes no sense because I intake so much water on a daily basis and have a very high fiber diet, well anyway I noticed yesterday I've developed what seems to be a hemorrhoid. I've never had any before and have an appointment with my doctor today and plan on asking about it but I'm pretty sure that's what is it. Never having any before I don't know what the deal is with them. I know they are common in pregnancy, but what can I do for it? And now I'm worried about getting more during delivery. How long do they usually last before healing?