Question
A person has been told that in the opinion of a doctor and/or rabbi (or multiple doctors and/or rabbis), they are able to safely fast. But they personally feel that fasting (or eating less food than normal) could be detrimental to their health. Are they permitted not to fast?

Question
What are the laws regarding a woman who gives birth to a boy? How long must she wait till having relations? Do all the rules of niddah apply like not sleeping together, touching etc?