The painkiller is Tolfedine. I was offered a choice of antibiotics: pills or the injection and was told they were both effective and that there wasn't any difference between them. I have given pills to Kira before; it's not that big of a struggle but I thought I'm saving her from more stress so I chose the injection. When I got the bill, I saw "Convenia" and I vaguely remembered reading posts about it.
If I had to do it again, I would take the pills instead. But she seems back to her normal self so...