I have this hot burning sensation on my lower back what could be causing it?I am trying to conceive.had a misscariage June this year from blighted ovum since then been trying to conceive.please help me .

Chances are the silent miscarriage and the back pain aren't really connected. There could be muscle or nerve damage that is causing the sensations in your back. Pregnancy, while will cause back issues, won't do so until you're a significant way into it.

Maybe go to your GP and see what they think of it.