Those 3 meds are commonly given together by knowledge rabbit vets when treating head tilt rabbits, from my own personal experience. Though always check with your vet if you aren't sure.
The dosage depends on the amount of active ingredient per ml of the suspension liquid. Meloxicam is usually the 1.5mg/ml suspension, and the usual recommended dose for rabbits is 0.3-0.6mg per kg of body weight, 2x a day. Baytril 5-10mg/kg, once or 2x a day, and the suspension mg per ml varies depending on how it was compounded, but it may say on the bottle or paperwork from the vet. Panacur (fenbendazole) is usually a 100mg/ml suspension, dosed at 20mg/kg, once a day.
Hasn't your current vet already prescribed the dosage for those?
https://www.vgr1.com/metacam/
Medirabbit: safe medications for rabbits
Then if your rabbit does have ear mites, that's another med that will need to be prescribed. Ivermectin or Revolution (selamectin) are the treatments generally considered safe for rabbits, my preference being the Revolution.
4 weeks is an awfully long ways away. Maybe you could present your current vet with your research and see if they'll work with you getting your rabbit on the needed medications for the right length of time? But if your current vet isn't proving very helpful and your rabbit isn't better, and you're sure this new vet is a very good rabbit vet, then I'd probably go ahead and book the appointment.
