Less serious side effects include: 1  Loss of appetite. 2  Weight loss. 3  Nausea. 4  Vomiting. 5  Diarrhea. 6  Frequent urination. 7  Muscle cramps, painful and swollen joints. 8  Excessive tiredness. 9  Difficulty falling asleep. 10  Headache, nervousness, dizziness. 11  Depression, mood swings. 12  Vivid dreams.
Nausea can occur in dogs for many reasons, particularly when the digestive tract and nervous systems are out of balance. Stress can certainly play a role in nausea.
He could just have an upset stomach from a switch of diet or stress due to some new changes in his life. Dogs eat grass to induce vomiting. Grass serves as nature's remedy for this purpose. If you see your dog consuming abnormal amounts of grass then he has a bellyache-but don't expect the grass to cure everything.