HELP!! does this sound like early labor?

Krista
I'm 24 weeks as of yesterday and my lower back (mainly on my left side) is KILLING ME. I can't walk through a grocery store for 30 minutes without ending up in tears. I keep getting this random sharp pain (sciatic). It literally brings me to my knees. I'm so afraid that my daughter is in danger from this. Since this pain started yesterday she has been less active and I can feel her sitting VERY low. I'm terrified & in so much pain. I can't even stretch to relieve it because it hurts so bad. Does this sound like labor? She will be my first born. My next doctors appointment is on the 12th so I've been trying to suck it up until then, but if it continues to be so constant then I may have to go to the hospital for this. Someone please tell me this is normal and I'm just being paranoid!