Trying to stop taking zyrtec (cetirizine) daily but feel head pressure / dizziness whenever i skip a day. any advice? allergies used to only be intermittent.

See a doctor: See a doctor preferably an allergist for evaluation and treatment. There are many treatment options available for allergies. There is no need to suffer.

Getting worse: This means that your allergic rhinitis has become worse. I see no problem with taking zyrtec (cetirizine) daily but given the progression of your disease you will likely need to see an allergist sooner of later.

Allergies: Allergies can be causing you nasal congestion that zyrtec will not control adequately, you probably need a nasal spray, see an allergist if you are dependent on medications, they may help you with better long term solutions.