Is the woman who do breastfeeding permitted to break the fast during Ramadan?
It is permissible for pregnant and breastfeeding women to break their fast during Ramadan if they fear harm to themselves or their child. However, they must make up for the missed fasts. If the fast is broken out of concern for the fetus or the baby, expiation (Fidya) is also required along with making up the missed fasts. The expiation involves feeding one needy person with an amount equivalent to a Mudd of food (approximately 600 grams of wheat or rice) for each day of missed fasts. If the fast is broken out of concern for the woman's own health, only making up missed fasts is obligatory. And Allah Knows Best.
Is it permissible for a woman to visit the doctor while in her `Iddah (waiting period)?
It is permissible for her to do that during day time, but it is impermissible for her to leave her house at night except for a sound reason. And Allah Knows Best.
What should a worshiper who has forgotten a pillar of prayer do?
If he/she remembered the forgotten pillar before offering it in the following Rakah (unit of prayer), then he/she should offer it, and continue the prayer, then offer Sujood As-Sahw (Prostration of forgetfulness) at the end of it. But, if he/she remembered that forgotten pillar after having offered it in the following Rakah, then he/she should offer a new Rakah in its (the one in which he forgot a pillar) place, and offer Sujood As-Sahw.
Does passing wind, from the anus without a smell, invalidate prayer?
If a person is certain of having passed wind even if it was with no smell, then both his/her ablution and prayer are invalidated, thus he/she should remake ablution and re-perform prayer.