Help? is my doggy sick? should i take it to the vet?

My 3 year old chocolate labrador retriever has had diarrhea for about a day because we have a pear tree and she eat like a lot. Now she is not eating. She will only eat her food with shredded cheese we put that on and she resists. I tried to feed it to her but she would only eat the cheese. The vet told us to put chess in it for a couple years. But she eats everything else like treats. She has been farting a lot and it smells like eggs. dad is like I will take her to the vet tomorrow. She is acting strange too. But my parents think she is fine but i don't think she is. Does she need to go to the vet? How can I tell my parents that we should get her seen? Thanks in Advance!