Stopped up nose, feeling like a lump in throat/scratchy, headache, nausea comes and goes/night have been taking zyrtec (cetirizine) not working well any suggestions?

Allergies vs URI: Could be a "cold" unless it happens every year at this time which means it is likely allergies. Or if it is going on longer than 3 weeks. We are currently in the weed season, although texas might still have grass and weed season. Add a salt water wash twice daily. Ask your doctor for a prescription strength nose spray which will work better than otc zyrtec (cetirizine).

See a pro: You listed chemotherapy as one of your procedures. If you are currently on or recently received chemotherapy your immune system may be depressed as a result and an infection is possible. So see your primary care physician. You may have a bad cold or a sinus infection.

Sinus infection?: You may have a sinus infection or a viral infection. If the symptoms last for more than 10 days or getting worse, see your doctor.