A strange thing happened to me when I got sick. I went from being outgoing and full of fun to becoming someone who would melt into the background.
Now keep in mind that I have, for the most part, an invisible illness. It isn't as though I would need to hide my health concerns by melting into the crowd. By all appearances, I am, well, normal. You could pass by me any day and wouldn't know that I was struggling or unwell.
Maybe you have done the same thing since being diagnosed. Perhaps you've withdrawn from people and activities. This behavior isn't uncommon for people with invisible illnesses.
If you feel healthy, strong enough, and have enough energy, there is no reason to withdraw. Remember, your illness may be invisible, but that doesn't mean you have to follow suit!