How long does it take for Nexium to begin working? I've been on it for a week now.?

I've been taking 40 MG, once a day, but I still have a continuous bad taste in my mouth, heartache, clearing of throat after meals, and sometimes numbness in my left arm (I DON'T have heart problems). One other note though... My seasonal allergies have flared up so I have a lot of post nasal drip, which can't be helping matters.