Severe stomach pain during periods, with weakness, is often due to strong cramps and blood loss, which can affect energy levels. Use a warm compress on the lower abdomen, get proper rest, stay hydrated, and eat light but nutritious foods like fruits and iron-rich foods to support strength. Gentle walking or stretching can also help reduce cramps. If the pain is very severe or keeps affecting you every cycle, consult a doctor for proper guidance and relief options.