Thanks for your query.
can be due to deficiency of vitamins,and even due to infection like candid.You can take a over the counter multivitamin(B-complex) tablets and apply mouth ulcer gel like smyle which is available over the counter.
Cervical spondilitis can give rise to dizziness
especially on turning of head.Please consult your treating doctor or physiotherapist and get advised exercise to strengthen neck muscle and the problem shall improve.
Since you have thyroid,diabetes
I guess you are on medicines for them as well as for pain of cervical and lumbar spine
Altogether these medicines can cause severe acidity for that you can take cold milk,over the counter antacid like Digene.If it does not get relieved consult your doctor and he will prescribe medicines like proton pump
inhibitor which will reduce your acidity problem.
Hope this answer is helpful to you.