What Causes Irregular Menstrual Cycle?

Question: Hi my girlfriend is experiencing some abnormal symptoms, she is 24 years old. She always used to have her period for 5 to 6 days but for past two to three months she is being somewhat late to her menstrual cycle. This month on her date she dint have her period instead she had severe cramps in her abdomen for one week, later she had her period (i.e 7 days late from her actual day) but the weird thing is she had her period for only one day which initially started with brown spotting and she had heavy bleeding normal like period ( bright red color) I think she changed around 5 to 6 pads. On second day she had her pain but very light discharge on third and fourth day she had very little discharge on fifth day she found some kind of brown mucus discharge which occurred only once. She often used to have white mucus discharge in her vagina but this time after her period the discharge was quite heavy with itching sensation, she even got some pimple kind of thing in her vagina. The discharge was thick white in color with itching and burning sensation along with this she is having constipation, indigestion problem. She says that her stomach looks bloating due to indigestion problem. We are not sexually active she is a virgin. This month she was put in to more stress and some restless night. She recently joined yoga class which altered her day to day activities. Normally her pain during the menstrual cycle will be more so she was having pain killers for past few years. She stopped using those pain killers for past 3 months. She even says that she gained some weight in her body and her breast has grown. For her yeast infection she visited OBGYN she had tablets and ointment within two days her infection was gone. But she was suffering from constipation so she visited the doctor who attended her during jaundice fever. The doctor suggested her for ultrasound scan and some blood tests. I am attaching the respective reports which she got it today. Please tell us what is her problem is everything normal, if there is any problem please let us know how it can be treated.

Her uterus report says

Pelvis:
Transabdominal sonography of the pelvis done.
Uterus measured 7.4 x 3.5 x 2.4 cms.
Uterus appeared anteverted with homogenous myometrial and endometrial echoes.
Endometrial thickness measured 5.0 mm.
Right ovary measured 2.5 x 1.7 cms.
Left ovary measured 3.3 x 1.6 cms.
Left ovary appeared normal.
No free fluid with POD.
IMPRESSION:
Left renal microlith.
- Please correlate.

USG Whole Abdomen Scan Report
Abdomen:
Liver filled with homogenous parenchymal echoes. No abscess or mass lesion in the liver.
Gall bladder appeared normal. No calculi seen in the gall bladder. Common duct appeared normal. No calculi seen in the common duct.
Pancreas appeared normal.
Spleen appeared normal.
Aorta appeared normal. No paraaortic nodes seen.
Peritoneal cavity appeared normal.
KUB:-
Right Kidney measured 9.8 x 4.6 cms.
Cortex and collecting system of right kidney appeared normal. No calculi seen.
Left Kidney measured 8.7 x 4.6 cms.
Cortex and collecting system of left kidney appeared normal.
Microlith in the mid calyx of size measuring 2.3 mm.
Bladder appeared normal.     

Could you please say me what does this report says. Is everything normal or is there any problem. Anteverted uterus is normal. Why Anteverted uterus occurs. Please give some detail answers.

Thanks for your response doctor. She remembered that she had same ultra sound scan two years before. She is saying at that time her uterus was normal but now it appears anteverted what would be the reason? Is that anything we should worry about?

Thanks for your answer Doctor. So the symptoms she faced during her menustration might be due to kidney stones. Does kidney stone can affect the menstrual cycle?