Hi, I get lots of pain during menstruation from past 2-3 months,it affects night sleep. Pain remains for initial 2 days mainly. I have regular menstrual cycle of 28-30 days. Duration of bleeding is around 4 days. I am living with my husband from past 8 months but not able to conceive. Kindly help me please. Somebody says it may be endometriosis, I don't have cysts.

Unfortunately pain is all too common, and there are many causes, and not all are treatable or even have a diagnosis other than 'pain of unknown etiology.'
If you know you don't have cysts, does this mean you had ultrasound?
Endometriosis, fibroids, tipped uterus, cysts are pretty much the standard conditions to look for.
But still, many women have pain without any of them. They take warm baths, do pelvic tilt exercises, use heating pads, reduce their diet and cut out caffeine and whatever makes you feel better, and take pain killers like ibuprofin and tylenol.
8 months is too soon to say you can't conceive. You try about 2 years, maybe more, before you wonder if both you and your husband should consider testing, which is expensive.