Dear Jenny,
I read your question and the first thing that came to mind is are you having regular bm's they can cause you a great deal of pain. If you are taking any kind of pain med they can cause that problem.
Constipated will cause you severe pain nausea and loss of appetite. The good thing is if it is that once you correct it you will feel great. what my doctor recommended was milk of manganisa another suggestion was suppositories. I hope this was of help.
Lisa C