20 weeks, worse morning sickness?

Li
Okay so I woke up today at 19 weeks and 5 days. Almost 20 weeks. I don't know if it's my morning sickness creeping back horribly again, or if it's a stomach bug. How can I tell the difference? 
At 7-13 weeks I had morning sickness all day long. It finally went away and only had it in the morning when I woke up. Up till today, I've had it all day long so far. Is it morning sickness getting bad again or a stomach bug? How can I tell?