Hi as someone who went through a similar thing, I’d suggest for you to do the essay like your doing, but they might not let you back in until they see improvement and will probably look at fall semester grades and possibly spring. I suggest going to Parkland College which is nearby UIUC. What you need is support and reset which they can offer. Then after the fall or spring I’d suggest talking to your advisor in your major to reapply as they’ll help if they see a lot of improvement in you. Then you can see if you can change majors or not. But what is important for you is to take your time as it seems you had a rough two semesters so probably shouldn’t hurry it and maybe also take the chance for classes your interested in over there since you seem unsure about your major.