Everyone is different, My daughter I had no signs of anything it was like the "perfect" pregnancy, my son the first 3months were brutal...and this pregnancy I am 26weeks for another boy and I was sick for the first month then nothing and all of the sudden the past 2months I have been sicker then a dog...It's nothing I would get worried about personally but by your next doctors appointment if you still feel uneasy about it, just talk to your doctor and i'm sure they will reassure you that everything is fine...Good luck with the rest of your pregnancy and hopefully the nausea goes away soon....Oh and also if it when you eat certain food that might be the reason also, I know if I eat hamburgers i'm done for and living in my bathroom for a good hour...
In my first trimester with this pregnancy I was sick as a dog! Then, during the 2nd trimester - no symptoms at all! Third trimester started 2 weeks ago and brought me dreadful back pain! Other than the things I listed, other symptoms hit me here and there briefly, but nothing that sticks around. I have had small bouts of nausea here and there since my first trimester and my nipples are sensitive, too - it's normal. :-)
In fact, pretty much all symptoms are normal throughout your pregnancy - as long as you aren't cramping/bleeding or having increasing contractions - like ones that get closer together and more intense, you should be just fine. :-) It's hard not to stress over each symptom as it comes, especially with the first pregnancy that you've made it this far with. I stressed about everything w/ my first pregnancy, but this time, since I have been there already, it's easier to stay calm and not get too freaked.