I get my periods on 18 date and from today it's...

The normal range of menstrual cycle is about 28 days and can be from 21 to 35 days .

Treatment of menstrual disturbance :

The treatment is being decided according to the cause of your symptoms after doing investigations and medical examination and determining the cause and then the diagnosis and treatment are decided by the doctor .

Diagnosis of menstrual disturbance :

The diagnosis is made by taking full history and clinical examination of the patient and doing investigations including blood investigations like CBC, thyroid functions, ovarian functions, blood test for pregnancy and pregnancy test in urine, estrogen and progesterone and testosterone hormones levels  and doing pelvic and abdominal ultrasound .

Causes of menstrual disturbance :

- vaginal dryness 

- Thyroid disorder

- Polycystic ovarian syndrome

- exhaustion

- stress

- severe weight loss

- obesity

- hormonal disturbance
- fungal infection 
- bacterial infection 
- pelvic inflammatory disease 

Advice :

See the obstetrician and gynecologist .