Dog is sick...anybody else dealt with this?

[cmrpoag]

My dog Lucy is a lab. Yesterday she started having diarrhea. We have medication for that, but you have to mix it with the food and she won't eat this morning. She has had to go numerous times since 1am. The last time I took her out the end of her diarrhea was blood(bright red, not dark). Is this just from the irritation from all the diarrhea? It is very watery. Yes, I have made an appointment with our vet, but they can't see her until 4pm. I'm just wondering if anyone else has seen this before and what the prognosis was. Thanks.
THe medication is a protecting coating for the intestine and stomach...a lot like pepto bismulth for humans, except for dogs. It was recommended that I give this to her, until we got the the point that it was very watery. I explained all the symptoms to the vet and they don't see it as an emergency that warrants us caming in now. They think its a parasite from all the mud we have had lately.
I'm not stupid when it comes to dogs...just so you know....she up to date on all shots and check ups. Not parvo, has that vaccine and all others. Medication was mixed with bland diet, as instructed by vet. She is sleepy, but not much more than usual. She did throw up, only mucus and not a lot.