Last Friday (not yesterday, a week ago), in a group workout, we ran ~25 minutes, then did 3 sets of 25 pushups alternating with 50 crunches, then played ulitmate frisbee. Ever since then, my lower back has been hurting to some degree. It was pretty much fine by Monday when I did my long run, but today it's hurting quite a bit again. I had been neglecting my core lately (for shame!), and I think I exhausted my abs, leaving my back to pick up the slack, consequently overtiring it.
Today I did some core exercises and awkwardly carried my daught partway up the stairs hurting it again/more in the process. Stinks.
I really need to do a workout today...haven't done anything since Monday.