Sounds to me like you are doing all that can be done. Except I take Motrin. If you can get your doc to prescribe the really good ones...they work.
Some days are better than other with this stuff.
Be careful with doing the exercises too soon. Give your back time to heal, then go at the re-strengthening the lower back muscles at a pace that you can tolerate. Always a good rule of thumb is, let your body tell you what you can tolerate.
How far down you nerve is your pain? Is it running down your thigh?
I will tell you what worked for me, but of course consult with your doctor before taking advice from random people on the Internet.
Because my spine was pinching some nerves, I had pain that was radiating down to my left knee. So the knee is actually where a lot of the pain manifested. My wife got this thing from Target called a “TENS” device. It is a small battery-powered device that emits a light electric shock into the area on which you apply it. It sounds strange, but it works. What it does is to fool your nervous system into ignoring the pain. The brain apparently gives priority to the nerve impulses from the TENS shocks, and so the impulses from the pain nerves never make it through. I found it really indispensable to give me some relieve so that I could rest and relax, which in turn helps with the healing. Almost certainly your physical therapist has heard of it, so talk to him/her if you are unsure. They also sell them at Amazon.com, and various drugstores, so you shouldn’t have any issues finding one.
The second thing I did was to get a steroid shot to relieve the inflammation. This doesn’t always work, but after talking to a couple of doctors, I thought it was worth trying before resorting to surgery. They also have relatively non-invasive surgical options as well. Basically they can use some sort of endoscopic device to go in and seal up the area where the disk is bulging out and putting pressure on the nerve. My sister is a doc and recommended I go this route, but since the steroid shot worked for me, I didn’t do that.
I went to Physical Therapy religiously on the schedule my PT recommended. The guy I went to is someone that was highly recommended to me by someone I trust, and having had bad experiences with lackluster PT before, I can tell you this made a huge difference. If you are going to one of those PT places where they just give you 20 seconds of instructions and then walk away, not to be seen for 30 minutes, then FIND ANOTHER PT.
After doing all of the above, I was feeling much better, but not 100%.
So the last thing I did was to start using an inversion table. Depending on your age, health, weight, cardiovascular situation, etc., that may not be an option for you, and you can hurt yourself if you do something stupid with it, so talk to your doc. I would also make sure someone else is around when you’re using it. However, for me it has made all the difference in the world, and I think is why I have not had a recurrence of the problem. Whenever I feel my back or neck bothering me, I hop on that inversion table and I am good to go for another month or more (I should probably use it more regularly). It takes a little getting used to, but it’s a safe way of inverting your body so that your spine can decompress. It’s like when you were a kid and you would hang upside down from the monkey bars or a tree. What I do is to do a gentle rocking motion on it, which creates an inverse pressure that tends to pull the spinal disc material back in. I also go fully inverted and gently rotate my head/neck and back to loosen and realign things. I do some other exercises on it, but you can read about those online.
The inversion table cures any issues I have with stiff/sore neck, and is much safer than going to a chiropractor and letting them twist your neck (that is actually a VERY risky thing). The inversion table I bought is from the company Teeter Hang-Ups.
PM me if you have any questions. I know how awful and debilitating this is. Hang in there, and keep doing the PT.
I developed a sciatica earlier this year and it was excruciating. A week or so into it, I found my way into the hot tub. Its weird but the second my body was fully immersed, all the pain vanished. No idea why but the hot water and the suspension of weight stopped all pain instantly. This was a real life saver. The first night, I actually slept in the hot tub, sort of. At least I was out of the pain. From thereon every time it got bad, I got into the hot water. This also allowed me to do full stretches which sped up my rehab. It was also crucial to visit a competent physical therapist. The man twisted me into a pretzel, but eventually the pain subsided and I got over it.
They key is the hot water. Not just a hot water bottle, get into a full tub and if at all possible, a hot tub where you can completely move around.