it started 2 weeks ago on friday, when I was doing a right side de ashi harai on someone and they stomped their foot down. as soon as my foot made contact I felt a dull ache in my back. so I stepped off the mat for a few minutes at which point it went away. it came back the following wednesday in practice after taking a poorly controlled fall, it lasted again for about 5 minutes, then it went away. same thing on the friday after that. this past wednesday there was no pain, then friday it came back, but wasn't as bad as previous times, but lasted a bit longer. it was still a little bit sore when I went to bed. then saturday morning I woke up with it still kinda sore, but went to BJJ practice anyway. doing forward rolls hurt, but only on one side (when rolling right hand forward). I didn't feel it at all while I was moving but as soon as I took a break it came back. after I got home it was really bad, and hasn't really gone away, though now (2 days later) it's not quite as bad.
I feel it when I'm sitting and lean to the right, when I lean down while standing, and every time I take a step with my left leg I feel it, and I especially feel it going up the stairs.
my wife says the lower left side of my back is slightly swollen, and the pain is only on the left side, the right side is fine. I don't feel any pain coming from my spine, it's all on the left.
what could I have done to myself, and what do I do to get better?
it goes without saying that I'll be taking at least a week off from practice. I've iced it a few times, and used heat. the hot showers seem to help a bit. usually when my back is hurting I use my foam roller, but that seems to actually make it hurt more for a little while so I'm not doing that anymore.