Thin Vittatus

[Dane]

I have a sub adult male Vittatus that I have raised from a juvie that is not doing well at all. Over the past month he has become more and more skinny, and I have often noticed him sitting with his mouth agape, or opening and closing his mouth repeatedly (unrelated to eating his shed). His tankmate that I have raised him with is doing just fine, and eating regularly, but I have witnessed this frog bullying the sickly one on a few occasions. This morning I separated the two into different enclosures in the hopes of eliminating the agression. They tested clean several months ago, and I won't have the money to get another fecal done for about a week. Can I do anything for him in the meantime? I have some panacur and some possibly expired metronidazole that I could try to dose with. Would a Pedialyte soak help?