Calling all armchair doctors

My ankle's hurtin' mama. Last night Jay and I went out for a couple of drinks and a light dinner. Later that night we were in bed watching TV and I experienced a sudden onset of acute ankle pain in my right lateral ankle...it kind of felt like a tendon or ligament had "locked up" and I couldn't really move my foot without terrible pain. I could keep it flexed upward but if I tried to move to the outside or point my toes flexing my foot downward it hurt really bad. Jason spent some time kind of massaging my ankle to see if something was pinched, but it didn't help. Oh, and pushing on the right side of my calf sent shooting pains down into the ankle.

This morning I wake up and it's just as bad. Doesn't hurt so much when I flex my foot upward, but letting it hang down naturally hurts and walking downstairs is a killer.

It's not swollen, and it's not discolored. I haven't been putting any particular stress on this ankle. I did work out a bit on Wednesday with some higher impact aerobics stuff and on Thursday with much lower impact weight training but took the dogs to the park on Thursday afternoon for a mile and a half walk with no problems.

What have I done to myself? I can't find an answer on the internets and my doctor isn't open until Monday. And if it is still hurting by Monday I am certainly making an appointment.