Open Question: how to deal with sore muscles after running and keep training?

I'm relatively new to the sport of running (started about 6 months ago, but not consistently). For the past 3 weeks, I've been on a traning program for an 8k race I have coming up in 3 weeks. I've been noticing that my muscles are sore. I know soreness is to be expected, but this soreness is worse than any I have experienced. It is basically there through my entire recovery day, and still there when I start my run the next day. I am a bit afraid to do my run tomorrow and am wondering if I should just cross train instead or just take the day off. Before I got on the training program I'd always wait for the soreness to subside before running again, but now that I am on the program, I don't want to back off. I also want to keep upping my mileage after the 8k. Any advice from veteran runners?