Can anybody tell me what movie this is?

There's this movie that I received as a gift in high school, and I no longer have but I want to get again. My only problem is, is I can't for the life of me figure out what it was called. It was made around 2003 I think. It's a vampire movie about a guy (with really dark hair) who is driving his boss's car across country where he comes across a hitchhiker. The both of them come across a blonde girl in a diner, who has some sort of breakdown and passes out or something. They put her in a bathtub with ice in a motel room, and they realize she had been bitten. (Sorry this is so all over the place, I only remember bits and pieces of it lol) I think the hitchhiker was a vampire but he was taking some sort of medications to slow down the process or something. There's a huge vampire human blow out in some farm house... lol. Again, I'm sorry that this isn't clear, like I said I only remember bits and pieces of it and it's probably not in any sort of order, but if somebody could help me that would be awesome. Thank you so much!!