My bike developed a noise whenever I squeeze the front brake, a clanking noise...

To test where it's coming from, I held the bike is stationary, squeeze the front brake fully, locking the front wheel. Now I push the bike forward... Clank!

I rock the bike backward and forward, each time when the bike was pushed forward, a "clank"!

That also is how I felt when the bike is moving, at the point when the brake contacts the rim, the "clank" noise is heard and felt. Then the bike slows down. Very disconcerting though with the "jerk" at the beginning of brake application.

I can't see anything moving while I did that. Nothing I can see from the bar, the fork, the brake...

On my way home, I stopped at a bike shop, the shop guy said it's the headset. Does that sound right?

Or, could it be the fork? Brake mount? Any suggestion on identifying which component is the culprit?

Thanks