Sounds like you need an MRI.
If the pop happened when you were extending your lead leg, it's possible that you tore something. It's a fairly quick motion that creates a lot of tension throughout the leg.
It's weird that it's the lower leg rather than the hamstring, but strange things happen sometimes.
If it's not black and blue, you might end up being ok, but the popping noise sounds like a problem.
Of course, maybe it was just a ligament crossing over a bone, causing a little swelling.....
If it's a problem you need to see a doctor. If it's actually injured, it's not worth racing, even if it's indoor nationals or something.
elevate it to keep down the swelling. Ibuprofen won't do much, and might actually hinder recovery. Ice maybe....who knows if that even helps either, and since it seems like a ligament thing, might not be the best idea (lower blood flow).
Btw, do you usually land on your heel when coming off the hurdle?
If so, this could be a problem. I think this causes a lot of issues in and around the achilles in hurdlers. You should be landing on the ball of your foot, although this requires more speed and good form.
Plenty of good hurdlers do it though, especially 300/400 hurdle specialists.