It should go throughout the 2nd trimester but it all depends on how your pregnancies going I'm 21 weeks and still get tired at least now I don't feel like I need to nap everyday .. I just try getting to bed earlier instead of napping and making myself busy:)
Very normal. The first trimester takes a lot out of you. As hard as it may be you need to make yourself get up and go out for a little. Even if its just a short walk.