I would do a normal but slightly larger water change.
To be honest, I avoid feeding bloodworms as there have been several instances of them contributing to bloating in frogs. In a barebottom or sand substrate tank you can try feeding live black worms (they will burrow into the gravel and die then rot in the tank) or feed a pelleted food (which is what I do for my own) such as HBH or Zoomed frog/tadpole bites. Or even the small size of the Reptomin floating sticks.

Keep an eye on your remaining frog and wait before getting any buddies for him. If you do get more, make sure you quarantine at least 30 days (preferably 6 weeks)