I have had a burning scalp for a few days almost constantly and today my saliva stings?

Get it checked out: Burning scalp and stinging saliva are not very specific symptoms of any particular disease. You need to provide more description of your condition and have a physical exam done. If you are not getting better or having other symptoms appear, don't delay - see a doc.

Many causes : Allergy to soap/shampoo reaction to hair colouring product hair products stress anxiety migraine side effect of medication occipital neuralgia sinus whiplash injury vitamin b 12 deficiency spinal nerve compression diabetes peripheral artery disease peripheral neuropathy sun burn chemical burn heat burn peripheral nerve trauma (see nerve symptoms) peripheral nerve compressions.