6mth old puppy grinding teeth, and making horrible noises while eating soft food?

[smc ?]

she has parvo, on day two of her treatment I noticed she was grinding her teeth, but I didnt think much of it, I thought it was because of the medicine because she didnt do it often, usually after she was given her round of medication. and now, after four days of nothing but fluids shes starting to want to eat, well I fed her some lunch meat ham - real thin slice (not good, I know, but she came up to me wagging her little tail looking at me with those cute little eyes and well, I gave in) while she was eating the ham, she was making the awfulest noise I have ever heard, like a really horrible crunching noise (like i'd just given her a thick bone)// I waited a little later and gave her some soft dog food and again, she made that same horrible noise.

I opened her mouth, her teeth look fine as well as her gums. but I did notice two of her back teeth are badly broken (I suspect from the grinding) --she'd never grinded her teeth prior to this, and the grinding started saturday (two days after she started treatment for parvo)

any suggestions on what this may be? it sounds horrible, i've never heard a dog make a noise like this what-so-ever while eating. (I will be calling the vet tomorrow first thing, but I just want to know if anyone has dealt with this, or knows something of it)
her treatment for parvo ends tomorrow, although shes already acting herself again, the grinding & noise she makes while she eats is bothering me. it sounds painful.