Feel like an old lady!! Nervous..

I'm 15 weeks tomorrow and I have been having a hard time feeling like I'm getting enough oxygen when I breathe, which is causing me to yawn, and now I have rib pain and jaw pain on my left side.. on top of that headaches every day and today my left knee started to hurt when I walk.. am I the only one who feels aweful this early?! I can only imagine how the rest of this pregnancy is going to go.. ughh.. some encouraging words would be really helpful.