I almost don't like to say this, but I'm having a similar problem!
I had a strongly positive Dix-Hallpike 16 days ago, followed by a successful Epley menoeuvre and strange as it sounds - to me anyway - I've had a headache more or less ever since. I've had to take ibuprofen every day since then, even though I'm keeping the total dose down to max 600mg per day.
In my own case I'm inclined to put this down to muscular problems. I normally do twice-daily exercises to put my osteoarthritic neck through its full range of movement, but stopped these for the two-month duration of the BPPV, as the movements produced spinning. Ditto when walking in the street - I unconsciously kept my head completely straight. As a result, my neck had stiffened up noticeably, and my head had to be forced quite painfully into the second stage of the Epley (turning it away from the affected side).
I'm not sure whether this would apply to you, as you're clearly much younger than me, but I suppose it's possible that you'd been keeping your neck very stiff when you felt dizzy, and even the less taxing movements of the D-H might have upset it.
Personally, I'm just going to wait this one out - unless the headaches suddenly start getting worse or I develop neurological symptoms, of course. In that case, I'd seek medical help asap. When it comes to health, I'm a confirmed member of the "wait-and-see" brigade, and prefer to ignore minor symptoms on the assumption they'll eventually clear up on their own. It usually works!
What comes to mind is that he or she may have stretched a muscle or two during the procedure, perhaps it was done too abruptly. The head should be guided in direction and not pulled.
Thanks for your kind words Liz, but I no longer have a sore neck, just a headache. That was the point I was making (as was Eleftherios I think).
If you google scalp muscles, you'll see that they form a more or less continuous sheet with the neck muscles. Add to this the phenomenon of referred pain, and a slightly pulled neck muscle could well be causing all your symptoms, even if you don't have pain in your neck. "Referred pain" means that pain in the muscles or blood vessels of the scalp is often perceived as being deep inside the head or the ear, as there aren't enough receptors for the different kinds of pain in that area.
I'm sure we'll both recover from our ills over the next few weeks. I also have the bonus of no longer having vertigo, so a bit of post-Epley suffering is a fair exchange. It's very liberating - I'm skipping around like a spring lamb now and making myself unbearable at work again!
I hope you can soon get to the bottom of your problems with dizziness.