Is it normal for my tooth to still be hurting 2 weeks after a big filling? i can't even chew food on that side or drinking cold fluids

See your dentist: The most common reason for pain right after large filling is that the filling is too high. See your dentist for post-op evaluation and minor adjustment.

Need root canal: It is possible that you may need a root canal because the involvement of the cavity is extensive

No: See the Dentist. 2 common causes for this. Most common is that the bite is not correct and you keep hitting on this -- get it adjusted now that you are not numb.Next would be that the tooth (nerve) is not able to recover from the accumulated trauma to this tooth (perhaps a very deep cavity) and cannot heal. You would need to have a root canal done, then a build-up and likely a crown. See Dentist.

Not really: Soreness should have decreased significantly by now. 2 possibilities: 1) Filling too high resulting in sensitivity. Minor occlusal adjustment will yield immediate relief, or 2) Nerve of tooth too badly damaged by deep cavity, and now root canal treatment is required. In either case we can't fix it for you. Please return to your Dentist for immediate care.