Hi.as per your letter,all the investigations are normal.Abdominal pain
on lower left side will not be a major problem.As Ureteric colic
and Gynaecological problems are excluded by Ultrasound
,most probable diagnosis is Irritable bowel syndrome(IBS
).Another possible cause may be musculskeletal pains due to sexual dreams which may be making your muscles stiff.So,you may be relieved after shower with hot water which relaxes your muscles.Nothing to worry.Its physiological.All the best.