Sir, Thanks for that detailed information. Regarding your condition Certainly Cervical spondylosis was diagnosed and you are using cervical collar,There may be 2 causes of the same. Firstly, the muscles which hold the neck may have weakened further having lost the ability to hold the neck and possibly causing turbulence in the inner ear that is giving you vertigo (GIDDINESS) . and to compensate the movement the vomiting is there.
Second approach to your problem is that sometimes Excessive
Calcium gets deposited in inner ear disputing with the balancing function and results in vomiting and giddiness. this is called as BPPV (Benign paroxysmal positional vertigo) .
Getting treated for the first i'll personally recommend you to start with neck strengthening exercises, (either with physio or without, but you should be consistent to feel the results)
for second approach first rule that by getting your blood serum Calcium levels tested and if they are high then stop taking SHELCAL on daily basis and consult the physician to titrate it and ween off. there are certain exercises for BPPV to be taught. consult Neurologist / Occupational Therapist / Physiotherapist (in order of priority). so that slowly vertin can be weaned off and most of our time that goes to sleep because of medication can be enjoyed by you.
Next Steps
Go for a blood test and whilst start off with neck exercises and don't worry.
Health Tips
Do it as soon as possible so that you are relieved from the trouble caused. STAY HEALTHY