BIG Coolant leak! Help!

So about three weeks ago i replaced the thermostat and housing on my 03 325i so i could get through DEQ and it was running great up until tonight.. I took my girlfriend to work and on my way home i noticed the coolant light came on with my service engine light at the same time. so i got home and waited for it to cool down. once it cooled i was going to put more coolant in to see what had happened and as i pour it in it is coming out the bottom onto the ground as fast as i pour it it was dark so it was hard to tell exactly where it was leaking from but it didn't look like the radiator. if anyone has any ideas on what to check for please let me know i will be looking for the problem in the morning. when i replaced the thermostat it was last minute and i was going on a trip so i didn't have time to get the recommended coolant (i know its stupid) but everywhere was closed except orielly's which didn't have it. I really hope this didnt cause the problem.



thanks in advance!