Agoprex is the brand name of agomelatine. 1-10% people on agoprex experience some gastrointestinal disturbance on it.
Next Steps
Consult your Dr regarding same. It may subside on its own after a few days. You can also try non Pharmacological treatment such as improving sleep hygiene( improve comfort of bedroom, avoid doing chores other than sleeping on bed, etc).
Health Tips
Do not stop/change dose of medication on your own.