If it is not pre menstrual tension or stomach cramps it is the problem of dealing with the menstrual flow. Technology offers sanitary pads, tampons or menstrual cups or caps to deal with the flow. The user has to decide what suits her best. Absorbent pads may be noticeable in form fitting clothes. They cause some soreness on the inner thighs.
Some women prefer tampon to external pads.
A plug of absorbent cotton or gauze is inserted inside. But these should not be left unchanged beyond six hours. Some brands state that tampons left unchanged for more than 12-18 hours increases the possibility of toxic shock. It is not clear what causes toxic shock. Absorbent tampons provide the medium for them to grow and spread infection.