7 weeks pregnant, should I be worried?

I'm currently 7 weeks pregnant and have been getting pretty bad morning sickness all the way along, from really early. Well the past couple of days have been terrible, I've barely been able to keep a glass of water down let alone eat. This morning I woke up and felt fine, no morning sickness, nausea anything. I even feel less tired. Probably a paranoid question but do you think I should be worried? Does this mean my hcg levels are dropping or something? Any advice would be very welcome thanks!