Oh wow, I'm amazed to see another front-line fighter on this board! Greetings! I hope you don't mind, but I'd like to share some tips. Note that if any of this sounds "New Agey," I'd simply like to say that these methods have been used by exorcists for centuries before the New Age movement began.
First, yes, it's quite possible to fall ill after doing these things, for several reasons. First, something nasty may have attached itself to you. If you pour salt into bath water and pray while bathing in it, you can cleanse yourself quite easily of whatever bad energy may have gotten stuck on you.
Second, it's best to "expel" spirits in the name of Christ, not "bind" them. I've come across one or two that can still react while bound, and it doesn't bode well for sensitive people staying in that house. Let's just say that their dreams can get rather unpleasant.
Third, if you're going to make a habit out of this, invest in some protection. Prayer will work, but you have to really keep your "holy armor" up at all times with a very strong visualization, in my experience. If you're one to lose focus, it's worthwhile to wear a silver cross, maybe carry some clear quartz and an amethyst in your pockets as well.
Finally, when you pray to expel spirits, try adding visualization. See your "holy armor" as a blazing golden light surrounding you, expanding to fill the entire room and burning away whatever negativity may be there. The most important thing when dealing with these entities is confidence. Confidence that would almost come across as arrogance if you didn't know better. You'd be surprised how many entities are culled simply by seeing how unwavering you are in your faith.
Best of luck, and feel free to message me with further questions
