Col, this is nothing you need to be ashamed about. Honestly, most people get these at some time in their life. If you can't go to the doctor and have something prescribed, go to your chemist and they will advise you on a suitable cream. Try Anusol, it is excellent!
Hemorrhoids can have various causes, see
http://www.general-surgery.co.uk/problems/haem orroids.htm
Try not to strain when you have bowel movements, as this will make things worse. I could give you more advice, but the link says it all really. Hope you feel better soon.