You need to distinguish between vomiting and regurgitation.
Regurgitation = directed at an object or person, food it brought up into the mouth and is manipulated orally , may be reswallowed, always voluntary.
Vomiting = no direction, head is often shaken and food material/mucous may be plastered on the forehead and sides of the face, rarely reswallowed, usually no voluntary control
Regurgitation is quite "normal" at this time of the year
Vomiting may be caused by thyroid enlargement, Trichomoniasis, Macrorhabdiasis, Candidiasis, Ingluvitis, Heavy metal toxicity, foreign body impaction and many others - basically SEE A VET NOW.