Major leg ache

Good morning all Early last week I put a thread up about my left leg which felt strange but after 2/3 days it eased a lot, anyway here we are, it’s woken me up and aches all the way down the back like mad. I’ve got up to walk around and it eases very slightly but it’s made me shiver with the feeling - despite it being pretty warm in the house. I’ve had some paracetomol to try and take edge off but it’s almost as if I have to breathe through it. Wonder if this is similar to others’ experiences? It’s not a sharp pain but a strong ache all down the back and it’s strong enough to not only keep me awake but I feel wide awake with it at 4am!