So, it's actually really common if you can't smell due to blocking issues in the nose, to also not be able to taste. When we can't smell, our taste buds don't pick up taste. Weird, right? But hold your nose sometime and test it. You won't be able to taste things with your nose held. (that's how my kid gets through eating something he doesn't like at dinner, ha).
You've been sick a fairly long time though. Maybe you had a virus and then got a sinus infection as secondary to it. That happens. Or have two back to back viruses. But either way, it's been long enough that I'd check in with your doctor. Maybe a round of antibiotics will knock it out. Have you had any fever?