Blood pressure really high despite meds? Cozaar 50mg/day. What’s going on?

I was in the ER for high blood pressure about 6 months ago. I went to my cardiologist and he put me on 50mg/day of cozaar. I cut out all sodium in my diet and have been on an extremely low sodium diet since then. My blood pressure still spikes all the time to 180’s/110’s. And it makes me
feel horrible when it does. I have chest pain on my left side sometimes and left shoulder. I dont drink and i dont smoke. My weight has dropped at least 15 pounds and continues to drop and i can’t stable it.I am 30 years old, i’m 6′3", and 220 pounds. I don’t think i’m that heavy. What is going on with me?