Plumbum

Hello all,
Hope everyone is doing well. I've had periodic success with Nux for treating chronic constipation. The constipation seems not to be due to diet - as I am a vegetarian and drink plenty of water and consume plenty of fiber. It seems like it is due to some spasmodic activity of the intestines. Like I've mentioned before, Nux has helped on and off. Lately, I have been back to this stasis like state of the intestines. There is only periodic urging with incomplete evacuation. Also, I have a strange feeling like the portion of my stomach imediately above the navel is drawn in - and, actually, unless I'm imagining it, it appears to be! There is a feeling of the rectum being drawn up as well. I looked at these symptoms and saw Plumbum as being a remedy. My only worry with trying is potency - i.e. I am very sensitive to remedies and do not want any effects of Lead poisoning! My questions to the practitioners out there are: 1)Has it been observed that Pb follows Nux for constipation?
2) What are the typical potencies for Pb for constipation.

I remember Dr. Sharma (Deoshlok) suggesting 3c/x sometime ago. Not sure if this was for acute conditions or not. Any thoughts, suggestions, comments etc. much appreciated. Thanks in advance.