8 Weeks Post TVH with Severe Lower Back Pain & Aching Hips - is this normal?

Hi, I am a newbie on this site and now at 8 weeks post-op from a total vaginal hysterectomy. I'm 43yrs and the main reason for my surgery was an enlarged uterus with multiple fibroids (they removed 2kg of them!) and all the symptoms that go with that. My hysterectomy went well but from the day after the surgery I have experienced severe lower back pain which has meant I can't lay flat on my back for more than a few minutes and haven't slept a night through since my op due to the aching pain in my lower back, upper glutes and hips (mainly hip flexors). Initially I thought it might be my sacro-illiac joint as the pain seems to concentrate around there but now it has spread across the back of my pelvis and up my lower back. A few weeks of Physiotherapy eased it a little but then it went back to being more intense and I am still unable to sleep more than a few hours at a time. Initially standing, sitting and walking was fine it was just lying down that aggravated things. Now sitting aches, standing for more than 30 minutes aches and lying down still hasn't improved. My urogynaecologist has been very good but unsure what the problem is and referred me on to a Pain Specialist as well as prescribing me some muscle relaxants which have helped me sleep more. I am wondering if anyone else has had this problem and how long it went on for? I've never had any back problems before but did have a tight hip flexor going into the surgery. I worked out twice a week and regard myself as reasonably healthy. Love to hear from anyone else who has had a similar experience.