Loosing weight?

Since i found out that i was pregnant at around 4-5 weeks, ive lost 10 pounds total and im currently 13 weeks. My doctor didnt seem too concerned but then again she did seem concerned at the same time. Idk what to do to gain more weight, everything i eat makes me sick and these past few weeks I’ve had headaches, stomach aches, ect. I just generally feel like crap all the time, Help?