It happens because Amoxicillin is totally overused in the USA.  Especially in children.  Personally, as an adult, I've used Amoxicillin a few times in the past because I didn't know any better, but I cannot use more than 250 mg at one time.  Most of the pills come in 500 mg doses which is totally too much for a child anyway. 

https://www.westernjournal.com/biden-admin-fda-adds-vital-drug-shortages-list-us-families-just-arent-getting-break/

Soooooo, instead of taking 500 mg twice per day (bid), I had to take 250 mg 4 times per day (qid).  Hey, that's just the way my  body is, it tends to over-react to certain drugs.  I don't like taking them anyway so when my body tells me something loud and clear, I listen - - and it DOESN'T like more than 250 mg bid to qid of Amoxicillin.  Make sure any child you know is not overdosing, because a pharmicist won't know that unless they go home with you (!).  Puking shorting after taking the stuff is a pretty good sign, so is a massive headache.  I'm not a headache person as a rule so even a slight headache gives me a red flag every time, that something isn't right.

Do you honestly believe a dork like biden is going to be able to deal with this type of thing?  I mean - - REALLY???  Ha, you're dreamin' just like all the rest of the dimwit dems.