Dog sneezed out food.

Hi there,
I have a couple of concerns. My chi is about 6 and a half years old. We got her when she was 8 months. She always had this problem of getting food, water, or anything else she ate up her nasl passage. Not sniffing it in, but coming through the inside (if that makes sense). She once had an incident with a blade of grass. We took her to Emergency, they gave her a shot of Prednisone. Wasnt getting better a few hours later. Loading her back in the car to go back, when she had a huge sneezing fit and the grass popped out her nose and landed on her head. This is on going it seems. She seems very sensitive in the nose department.
A few weeks ago she was getting a treat of soft canned food (blue buffalo). She eats...well like a piggy. In the middle of her meal she starting sneezing and hacking like mad. I knew what happened. The thing is she never got better even 2 weeks later. She was still sneezing and what not. We took her into the vet. He said could be a few things. Something in her nose, a bad tooth or a nasal tumor. I didnt feel good at all when he said that. He gave her a 2 week antibiotic shot. A few days ago she was sneezing, big ones that her head almost hits the floor. I seen something come flying out. It was some soft dog food! I thought whew...she will get better now. She has improved, but is still a little congested and sneezy at times. Could there still be some in there? Or could it be that her nose is very irritated? She has a clear mucus running a lot at times or when she is sneezing. A few times it looked a creamy to very light yellow. Mostly clear though. I'm scared to death about the mention of the tumors, as I know the outcome of that. We just lost our border collie last month very suddenly to heart failure which left us heart broken. So maybe I am being paranoid? She is a tiny dog, little less then 5 Ibs. I'm so worried. Is it normal for dogs to frequently get things in the nasl passage from eating or drinking? We have a Yorkie her size as well who doesnt have these issues. I would appreciate any thoughts you may have.
Jessica

She did have a dental cleaning a couple years ago. They never mentioned anything about her palate. I wonder if that is something they would notice? He did say she was due for a cleaning again. I try to brush her teeth, but with her flayling around she makes it near impossible. He also did mention her gums were a bit red near the tooth line. I did give her a bone to chew on though, so maybe that contributed to the redness? She doesnt normally get bones. How long would it take a nasal tumor to progress? She has had these troubles her whole life....so surely she would have been gone by now? She has always been a sneezer. The reverse sneeze as well as a normal sneeze. She is eating and drinking normally, we have been blessed with great weather lately so she has been enjoying her walks. If there is soft food left in there, could that cause problems for her? Or would it eventually makes it's way out? Thanks again.