my sick cat wont eat and peed in a random spot?

[eutopia]

So i took my 2yr cat to the vet today and he said she has a cold and gave me antibiotics. But she hasnt ate a thing today. I dont even think she drank water. Im pretty sure she didnt eat yesterday either. Now, she peed next to a door when her litter box is down the hallway. She NEVER pees anywhere else other then her litter box. when will she eat and how long can she go like this not eating?! Also should I try forcefeeding her with soft liquidy foods? please help