Hello, 
However, tiredness usually occurs due to generalized poor health, anemia, diabetes, thyroid problems, 
chronic fatigue syndrome, lack of adequate sleep, stress, 
depression & anxiety, an early sign of 
pregnancy in females.. Get physically examined, get total health check-up done. 
Nausea is usually due to 
acid reflux, migraine, liver dysfunction, 
dehydration or excessive tiredness. Get evaluated, get treated. Your treatment will depend upon the illness detected. You can take anti-emetics, antacids & vitamin supplements to feel better. Stay away from addictions if any. 
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. Nupur K, General & Family Physician