Yoga - March 23 (4:30 PM class)

So, on the way to yoga today I'm thinking, "the 4:30 PM class is going to be soooo hot (because it was a hot day and afternoon classes are always hotter than my 6:30 AM class)...it's going to kick my butt." Well, it was hotter but it wasn't harder. It was actually easier. For some reason, I felt super strong (but alas, my back was bugging me). My legs felt strong and I didn't even mind Awkward Pose (and that's unheard of!). I reached my goal of "locking my knees" in Half-Moon with Hands to Feet Pose (second set). My goal was to do it just once, and just once it is going to be (for a while) because my hamstrings are going to be sore tomorrow. I also touched my head to my left knee in Standing Separate Leg Head to Knee Pose. If my back was 100%, it would have been a great day. It hurt in Fixed Firm and it was down hill from there. I have 8 days left in my challenge and I'm concerned that the strain is not going to heal properly because I am not giving it a chance to rest. I guess the next 8 days will be a test of that. Can an injury heal if you continue to exert it?
PS - My back felt great at the end of yesterday and all day today before yoga. No pain. I drank more than 3L of water yesterday and I'm thinking that has a lot to do with it.