((BiscuitTin))
A few thoughts for you.
When I read your post, I thought about a grieving process.
Being faced illness can cause grieving of the life we thought we had. It is a major shift in how we view ourselves and this thing called life.
IMHO, your body is trying to heal from the period of high anxiety, and a certain amount of feeling 'flat' would be normal. Just like our taste buds work -- if we have a piece of really sweet candy and then eat some fruit, we might not notice the fruit's sweetness. We need time to regain our equilibrium.
Take time to care for yourself in this period. Maybe talk to someone, eat really good healthy food, and get out for some fun. Basically, nourish yourself, in every way that you can.
HTH -- feel free to ignore any and everything I said if it doesn't