Hello, friends

I grow garlic for a few years, have a good harvest with nice sized bulb, but this year, I have no idea what had happened, 90% of my garlic top are yellow and fell down like 2 week ago, I dug out a few, tiny small bulbs, I have music, and those use to be a large bulb, now is only half inch baby bulb, the whole bed of shandong with XIan are disappear, the seed I purchase online garlic farm.
Is any one in my zone area have same issue or just me?
I feel so bad about it. I am not sure if I can use it as seed for next year.

Help please
Thank in advance
Wendy