Everything is back to normal. We can all sleep again. Myst had dilated eyes and acted insane - meowing without ceasing until he got hoarse as a side effect of the appetite stimulant he was given and nobody could sleep around here except Dandelion (the master at sleeping in this house).
The medicine is out of Myst's system now. He has healed well. He looks completely back to normal and is eating and chasing me again (yay!). Thank-you for all of your comments and support. Life is good.