Ouch! pain

Yesterday nite, i was trying to b hardworking, so i locked myself in my room to "practis" my cheer stuff. Start from warming up *stretch..stretch*. but when i arch back tat time, PAIN! cannot hold there, so i go down to bridge. but went i wan to stand up, I COULDN'T! :( Why lik this arh? i noe tat my back start to pain few weeks ago, but last week when i do bridge or back exercise, still okay de.. i can even do a "elbow bridge".. hahahaha.. but now.. i can't do a ARCH BACK! *sniff sniff*