I'll take any pain relief tips as well. She gave me a script for morphine but I had an allergic reaction.
With the twins, I got close but I didn't carry them nearly as much as my others so the back didn't go out. About 9 months PP, I started with the Tupler exercises to work on my diastasis and core muscles. My back has been better since.
If you could get to a SKILLED PT (doc referral), that would probably help immensely. You'd want a large enough PT group that they'd have massage therapists on site. With some good exercises (core strengthening) and massage work, you'd get relief a lot sooner than without. Seriously, it would be worth the time.
You are probably going to seize up if you try to get through this on your own. All your other muscles are going to start acting abnormally as they compensate for the pain and inflammation. I tried to tough it out with a lower back injury (same thing- just carrying kids around and pulled it) and I eventually couldn't walk. Everything was spasming. Went to a really awesome masseuse 2x and she completely relaxed the muscles around the injury and allowed everything to heal. It was very quick healing after the first masseuse and I was walking bent over and shuffling trying to get to the appt. - walked straight coming out of it.
I know you don't have time but it will save you time in the long-run!
I used heat to relax the muscle - that helped a lot also.