uri Felicity update

So I brought Felicity to the vet since she was having some respiratory problems. He said that the infection appears to be viral, and so there is little point of giving her antibiotics unless it is a bacterial infection. He gave me this stuff call Viralys with Lysine. Now I'm not sure if I should just give the stuff to her or if I should put it in her food. Does anybody know anything about this stuff?? The other cats scarfed it down when I put it with their food, but Felicity won't touch any food so I don't know what to do.
They tested her for feline leukemia and fiv.. I don't know if those are the same thing they took som blood, and gave her some fluids. And when we got home she started drinking, which she hasn't done in a few days. I'm just concerned. Any helpful suggestions or good vibes are very much appreciated.

is it a pill or liquid? you may have to use a pill gun or a syringe and give it to her

it's a paste. The vet told us to put it with her food, but the problem is she refuses to eat, and now I think she has diarrhea. We tried to feed it to her with a syringe, but she is a very finicky cat (she came from a background of abuse) and she absolutely refuses to let anyone touch her head, she totally freaks out and throws a fit. I don't know what to do. I can't make her eat this paste and she doesn't seem to be improving, although I think her breathing's a little easier this morning.

We brought her back in today because she seemed to be getting worse. The vet gave her some antibiotics (Zenequin) and an antihistamine (Novo-pheniram) He also gave us an electrolyte solution that she's supposed to drink, but she won't drink it. I don't think I can handle any more of this, my brain's about to explode. I just wish she would get better.