Thanks for reply Brian,
I thought it was downtime, till I see almost everyday my website down for 2min to 30min and I notice it was my cpu usage overlimit while I check in cpanel.
For a beginner like me who don't have backend knowledge about cpanel. There is no email notice that my shared is hitting a limit or I need to upgrade my server because the limit. Even when I submit the ticket, it give me a vague answer that I already follow it but the problem still there. It's kinda make me frustrated.