Sinus / Allergy?

As you know I've been struggling with this strange cold the last few weeks. It started out with just sneezing, no big deal other than a mild annoyance. But as time passed I started to feel tired, fatigued and just plain off. The only symptoms I have is the sneezing and a constant headache. After talking to my Mom I think it might be allergy related so I wanted to ask...

Do any of you know if allergies or sinus problems can cause you to feel just plain tired and crappy? I thought all it did was cause you to sneeze a lot. If so, what are my options really? I can't have antihistamines because of Annabel. Do I just have to grin and bear it?

I also should mention tomorrow I'm heading in to see the Neurologist who has decided to try me on a TENS machine. We'll see how it works.