I have severe low back pain, can I call for an ambulance.?

I have severe low back pain, severe pain on both flanks but acute on the left (can't stand straight as a result) Pain in the abdominal region, severe chills. I wake up every morning and cant move an inch from the bed unless I take 2 x 200 mg of neurofen. I would have to lay there another hour for it to take full effect. It all started mildly in Feb this year and I have seen my GP severally, test & scan done but nothing comes up so I end up getting pain killers and a worsening situation. I felt the worst pain ever today and passed out briefly. Despite taking 2 neurofen 2 hours, I can feel the pain creeping in. I cannot get off the bed. Can I call an ambulance for something like this? I'm in the UK.