Can sinus or allergies cause numbness in hands and feet?

Look for other cause. These do not usually cause numbness in the hands or feet. There are a number of other causes, especially diagnoses such as diabetes or other metabolic or hormonal disorders including thyroid problems. If these are happening regularly and are not from resting on a nerve, you should have it checked out.
Usually not. Numbness in the hands or fingers is usually caused by nerve compression such as carpal tunnel syndrome. There are a number of causes for this including diabetes, hypothyroidism, trauma and most commonly we do not know the exact cause. An evaluation by a hand surgeon with appropriate diagnostic testing can confirm and treat this condition.