"Medical certificate "

So I need to go back to my country for urgent matters. But my office will not give annual leave due high demand of workload from client. But my leader give me hint to use sick leave as the excuses.

Anyone in here know about buying "meds certificate" for 2-3 days? Please let me know if there are any clinic or doctor can provide this "service" or you can dm me for the details. I really need it. Thank you. Kha poom