I think it's more than being out of practice. It could be anxiety. You haven't done this and inside you aren't yet comfortable with doing it now? It could be a medicine you are on. It could be age. It could be someone more important that needs to be checked out. If you try various remedies and the problem doesn't improve, or worsens, I would suggest you then schedule an appointment with your MD. Just my POV.

Are you stumbling over any kind of word, or maybe just larger ones, or bigger concept words? Are you using new words instead of old familiar ones? Try thinking of the first syllable only, and then allowing the rest of the word to come.

Perhaps you are rather excited to share, and your mind is going faster than your tongue Try breathing slower, and try reducing the urgency to tell others what you will share. Speak more slowly over all, and even if a word fails to show up, it won't be so obvious and you won't stress out so much about it.

Good wishes!