Can sinus problems and allergies cause muscle aches, neck pain/stiffness and full body aches?

Probably not: Sinus infections can not directly cause body aches. Upper respiratory allergy does not usually cause muscle aches and neck pain. A viral infection of the upper respiratory tract can produce all these symptoms. If so, be patient, drink a lot of fluids and your immune system should kick in. If these symptoms last for more than 10 days, see your physician.