Something is wrong with my dog, please help?

Ok first off, dont tell me to go to the vet. We're bringing her tomorrow. But i need opinions and help. Her name is Marki, and she's a 3 year old German Shepherd. She's been a happy healthy baby her whole life, now all of a sudden she's been acting really strange, particulary at night. She still eats (normally too, kinda like she's extremely hungry, she wolfs her meals down really fast), but she doesnt drink. I've only found her drinking very rarely, and she doesnt even drink that much when she does drink. Its really hard to describe whats wrong with her. It seems like something is going on inside her, she'll all of a sudden jump up from laying down, freak out, and get as close to me or someone in my family and will stick to us like glue. She will get so scared, she wont leave whoever she's with, this is soo bad she has tripped us up many times, she almost knocked my mother over. You can see in her face that she's petrified, she gets so worked up she's panting (BUT WONT DRINK!), and she looks toward her back end. At first we thought maybe she was farting and it just scared her, but in a disgusting way, we found out it wasnt farts. So we thought their was something wrong inside her, her stomach or something. We went to the Vet, and we were told that she had a intestinal infection. We were given the proper medication that would get rid of it. Then a week later it happened again, so we got the meds again, didnt work at all! We also had her checked for tapeworm, nope. So she's going again tomorrow, but not before i get a better idea about what could be wrong with her. The other problems i need to add before i ask you to help, is that she also wont pee, only about every 12 hours, same with pooping too! She even went over 24 hours without either a couple days ago. plus like i said before, her appetite is perfectly fine. Please if you have any idea's, let me know! I'm sorry the description is so long, but i cant help it. Please help.