Jaw pain and headache after getting porcelain veneers and crowns. Do I just need some adjustment time?

There may be a problem with your new bite, however the most likely cause for your pain is having your mouth opened wide, wide enough to have dental work done for long period of time. Some can only tolerate short procedures being done in a single appointment or they will have post-operative jaw pain. If you recall your jaw or joints beginning to ache or become fatigued during this dental appointment, it is very likely that 
If this the cause of your pain, you will find:
You have pain when you open wide   You have pain when you bite down or clenchYou may have pain in or near your ear, temples, back of your head, eyes, shoulders, shoulder blades
Start by treating this the same way you would treat a sprained or strained ankled...
Rest - this means a soft diet, no chewing gum, nuts, ice, etc Medicate - with over the counter pain relievers that have anti-inflammation properties like ibuprofen, up to 800mg every 8  hours if this is a drug that is safe for you to takeWarm compresses t-help surrounding muscles relax
If you don't experience some relief after several days of committed rest, it is reasonable to consider other causes. It is also important that you wear a protective guard if you are clenching your teeth, to keep from breaking your new veneers.