Caminero has walked 13 and hit three in 17 innings. He is 0-2 with a 5.19 ERA in 19 games.
"Guys need to keep the ball down and away from the head area," Diamondbacks manager Chip Hale said after the game. "If a guy can't do it, then he has no business being up here in the major leagues."
Pirates manager Clint Hurdle said Caminero had no intent to hit either batter.
Segura said Caminero apologized via text message Wednesday morning.
"It was one of those difficult moments that you don't want to ever happen in baseball," Segura told reporters.
Added Ahmed: "It sucks. You don't want anyone to get hit, especially in the head or the face. Two guys with the same pitcher in two innings, honestly, I don't think he was trying to hit me ... but still, you can't be throwing up into guys heads."
"This game can be hard, and when you get players hurt, you're going to feel angst," Hurdle said. "I understand where Chip is coming from, but I don't agree with him."
Watson can miss up to three days with pay while on paternity leave. The primary set-up man for closer Mark Melancon, Watson has made 10 consecutive scoreless appearances.
Lobstein and Scahill are both in their second stints with the Pirates this season.
Lobstein was 2-0 with a 4.79 ERA in nine games with Pittsburgh. He made one start for Indianapolis and pitched four scoreless innings.
Scahill had a 6.00 ERA in eight games with the Pirates and had a 2.89 ERA and three saves in nine games at Indianapolis.
Information from The Associated Press was used in this report.