SAME PAIN BUT I FIGURED IT OUT: I had a similar experience but I have finally figured out what I was doing wrong, and for me it was a mechanical thing!
I have not been on this site in a year, but wanted to see if anyone else had the same issues that I did with my THR, right hip, anterior (2015). I first had groin pain and I could not drive without burning sciatic pain after 45 minutes of driving (about first 6 months, this is pretty normal). This finally dissipated after about 9 months.
Then the groin pain moved to the front of my leg (quad area). I would stand up and then limp for the first 3-4 steps and then my leg/hip would be sort of OK to walk on without that intense pain, but it still was painful. When I lay down, I had intense pain and as I was getting up off the bed, it would soar to a 10 pretty quickly., quite searing.
I sleep with a pillow between my legs and always on my left side (THR was on right). I was so exasperated because after I felt the intense pain, when I walked around there was still residual pain, much more than soreness, but not intense as the pain when I stood up from a chair or when I got out of bed. I would often favor my right leg a bit when walking too, and my hip would not feel "settled in".
I finally decided to go back to the basics and if that didn't do anything, I was going back to the surgeon. (BTW, all my checkups showed the hip was beautiful, aligned and healed, etc. perfectly !!) I started paying attention to how I got up out of bed and out of a chair AND I WAS DOING IT ALL WRONG (AT LEAST FOR ME). I was getting out of bed by swinging my fully extended right leg onto the floor, then sit up and then swing my left leg on to the floor, with my body kind of sidewise-ish to the bed. When my right leg was fully extended I would feel like my muscles were pulling my hip down and out, such crazy intense pain! When I got up out of a chair, my legs were not straight together, as in my knees and thighs were not completely parallel with each other, so they would be spread apart and at an angle.
I decided to change this by following immediate post-op advice: I scootched up with my elbows to sit up in bed, until I was in a full sitting up position on the bed with my legs extended in front of me; then I put my right leg on the floor, completely at a 90 degree angle to the bed then put my left leg next to it. When they are STRAIGHT and EVEN, I stand up without leaning far forward, in other words, I engage my core and push off a bit with my arms with a straight-ish back. NO PAIN WHATSOEVER!
Same with a chair: knees and thighs parallel, keep my back as straight as I can and do not lean far forward, and VOILA, absolutely no pain. Apparently the mechanics of leaning forward and having my legs at angles would stress my hip, I would feel this searing pain, limp for a few steps and then kind of shake it off but still with residual pain.
Now I HAVE NO PAIN WHATSOEVER WHEN I GET UP, and feel pretty stupid I didn't pay attention to this before, but am thrilled to have found this out. I don't know if this will help you but it is worth a try. And I too got regular massages, I go to the gym when I can, try to be active (nothing really helped) but the pain got so debilitating mentally and physically that I was going out of my mind. Now I understand when people with THR say they are pain free, I am virtually 80% and getting better every day. It is a miracle, plain and simple. GOOD LUCK!