36 weeks having contractions. some are painful some aren't that bad &' im having back pain &' period like cramps? is this braxton hicks or real labor?

Possibly: Back pain and contractions are signs of pregnancy but it depends. If you use a watch and time the contractions and if they seem more consistent and closer in time apart then that could be a true sign of labor. I would call your OB/GYN and discuss and other specific symptoms. These symptoms include and vaginal discharge, water, etc.

Contractions: At 36 weeks it is important to follow your doctor's preterm labor precautions. These might include: more than four contractions in one hour (BH or otherwise), vaginal bleeding, an increase or a change in the type of vaginal discharge — if it becomes watery, mucusy, or blood-tinged, more pressure in the pelvic area (a feeling that your baby's pushing down), low back pain, etc. If so, see doctor.