You need to get a couple of investigations done:
1. Pelvic ultrasound
and ultrasound abdomen.
2. complete hemogram.
3. Liver function tests.
4. Thyroid function test
Do not worry its nothing very serious!
Once you get the investigations done the cause can be easily pointed out.
1. A course of pantoprazole- domperidone
combination like Pan D tab before breakfast for about 15 days. ( just observe if your pain , nausea and bloating sensation of abdomen subsides )
2. Oral antispasmodic like dicycloverine
hydrochlodire tablet only if lower abdominal pain
3. For lower back pain see with hot formentation first. If it does not help you can try oral medications like aceclofenac
tablets as required .