Anak, please go to your OB or the hospital right away para ma-check properly, back pain with that kind of discomfort at 36 weeks needs a doctor's assessment, especially with the pressure and everything that happened. Hindi ako makakapag-advise ng sure dito, kasi kailangan talaga seryoso tingnan ng doctor mo.
One of my mum friends had something similar and kinailangan lang ng check-up para ma-assure, so go na, 'cause peace of mind lang din yan para sa'yo at baby mo. Dali na po!