I'm so sorry, something took him quickly and drastically.
Was he from a store or breeder ? He may have had atadenovirus [ ADV ] which is semi common in beardies and can kill babies quickly. Sometimes eating large crickets that they can't pass can also be fatal, how big were they ?
I'm so, so sorry that this happened. I know that your heart is broken so people here can help you grieve, many of us have been through the death of a beardie and we know it can hit hard.