I don't know if you could actually call what dogs get stomach "bugs" but yes, they can suffer from GI issues. Sometimes when they eat grass it results from a natural instinct to purge themselves of some offending intestinal issue. In other words there stomach doesn't feel right.
What is going on with your dog, I can't say, I could only guess. So taking her in for a check especially if you feel that she is uncomfortable is highly recommended, your vet may want to check a fecal sample to check for causes that could range from parasites to bacterial overgrowth in the intestines. If she is a dog that has a habit of getting into things or chewing up toys, clothing, shoes, etc. these present another concern of chemical ingestion to obstruction.
Mind you I am brainstorming here, some of this may not apply to your dog, but I would advise a check over, if she is not her normal bouncy self.
Good Luck I hope she is feeling better soon.