Is this just a cold or should I go to the doctor?

I never usually get sick but once in a blue moon I do and it lasts a few days maybe a week - but this is going on two weeks. I am still congested and have been getting headaches (not migraines). I also can't get rid of this cough...it isn't deep in my chest but it is still present, and too top it off I have constantly been feeling nauseous. I don't know if this matters but I haven't been getting good sleep at night, lately. Could that be a reason why I don't feel so good? Or is it just a cold and I should get some Tylenol Cold..or should I go to the doctor? Thanks