Premature greying. First. please help.

Hello I am 23 years old and have started experiencing lots of grey hair especially on my temple and in the front. I noticed very few strands around an year ago and they have since increased in number around the same regions. I got my B-12 and Thyroid checked when I first experienced greying which came out to be normal. My diet has not changed much over this period of time. I have definitely been eating relatively healthier in fact (almost daily intake of any fruit, chia seeds, dry fruits, etc.). My stress levels have been moderate to high over the past year but for the past few months it has been moderate. I cut my grey hair close to the root to hide them but not only do they grow back the same, I notice more grey hair around the same areas where they started to appear at first. Please help.