Hello,
Bloating and hardness of stomach can be due to premenstrual symptoms. It can be avoided by taking a balanced diet rich in proteins, vitamins and minerals. Avoid excess caffeine, alcohol and smoking. Indulge in mild exercises everyday. But if problem persists please consult a gynaecologist.
I hope it helps. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Hardness during your period is normal. Although you might not experience this all the time, periods can be random at times. If you continue to have problems, see your gyno.