Am i getting sick? D:?!

I've been feeling kind of drowsy lately, my throat feels weird when i swallow, i've had a slight headache for about three days now (which is not normal for me), and i've been getting a really stuffy nose (especially at night time). Also, the weather's been really crazy lately (REALLY hot, to REALLY cold). Could i be getting sick? I have a very important week next week and i'd really like to fight this now rather than later.
Do you have any remidies you could suggest??
Thanks :)