What are those pills that David Bryan had?

I can see those pills in one of the Access All Areas videos.
Also in the Guadalajara video from 1990.

The pills from Guadalajara 1990 were taken by him probably because of the stomach virus he got at the end of the New Jersey Syndicate Tour in South America.

That probably would explain why he didn't really smile or anything when Alec took all the pills in his own (Alec's) mouth.

He was severly ill at that point and lay in the hospital after the tour had ended for two weeks, plus being bedridden at home for four weeks after that.

It was actually parasites, not a virus. He nearly died.

The next hiatus, he cut off his finger.

Hiatuses are bad for David’s health.

Yes, he even described the parasite by saying something along the lines of - " It ate out my stomach". I'm not sure if that's the exact quote or not.

I'm pretty sure that these are almost the words he used in the WWWB documentary book.