10 days really isn't a lot of time when it comes to bunnies recovering from things like this. (has EC been tested for as being the cause?) I have read many stories where it has taken at least a month for owners to notice any real improvement in a head tilt, with it taking several months for a bunny to fully recover, and some having a permanent head tilt, however in most cases the affected rabbit learns to live with it. So I would say that it is still way too early to expect any real improvement to the head tilt. That being said, if her overall health is deteriorating then you are definitely doing the right thing in taking her to the vets tomorrow, and hopefully they should be able to offer some suggestions.
Is she on Metacam for pain relief and anti-inflammatory properties? This may help her feel more comfortable, and also help with the clinical symptoms (head tilt) as they are caused by inflammation. Also, have you tried feeding her herbs and fresh grass as this is often the go-to for bunnies that are feeling poorly? As awful as it is and as bad as you feel when syringe feeding them, it is important that you persevere with it and keep on top of it, especially if she isn't eating anything on her own. The vet will probably give an injection of a gut stimulant and may give a oral gut stimulant to you to give her at home to keep her gut moving properly.
I know it's scary when they are poorly and especially when they don't seem to be improving, but as long as you monitor her closely, keep on top of medication and get her to the vet first thing tomorrow morning, then hopefully she will be be OK
Good luck tomorrow and do let us know how you get on x