So I'll try to keep this as short as possible but I have a tendency to ramble.
Started undergrad at a community college, no future major in mind. First semester had a B and an F. Took a year off school, then went back, started doing much better, retook the course I had the F in and got a B. In the first full year probably withdrew from 2-3 courses but did well otherwise. Graduated with an AA and a GPA of ~3.5. Started at a university and continued about ~3.5 GPA the first year. Second year meant the grad application process was started but being a transfer I had to take the courses in an untypical sequence, and ended up with two upper level labs and three other courses in the Fall. I'm used to heavy work loads so this wasn't a huge issue, but the issue was I started getting constantly sick. Ended up withdrawing from two courses that semester, switched from a BS to a BA, and then took an incomplete in one of the courses I was still in. Now I think I sent transcripts out after the incomplete went on there, so I'm telling myself that's why I didn't get in anywhere. That and I applied late or right at the deadline.
Anyway now that I'm not going to grad school next year I'm coming back for another year to finish the BS that I had switch, and get a Math BS as well (it's actually not a strict math degree, but has a focus into my field, basically a few courses more than a minor, a few less than a pure math degree) so that's all good, but my health has still been terrible this semester too and in fact my doctor still doesn't know what is causing my blood test results as all of the usual suspects have been ruled out. I've gotten so far behind and struggled to stay caught up, my GPA suffered quite a bit this semester I'm sure. I've pretty consistently gotten about a 3.5 every semester of college (save that first semester where I had an F) up until now. This semester, I'll be happy if I end up above a 2.5 but not shocked if I don't.
So my question is, what is the best way I can explain that it wasn't a case of senioritis or me getting lazy towards the end of my degree? Outside of that my application will be pretty strong. I'll have about 2.5 years of research, GRE scores I'm pretty satisfied with (81st percentile Q, can't quite remember verbal at the moment, somewhere around 60th percentile or above, AW I think was a 4) Subjects GRE could have been better, but I was also sick all throughout when I should have studies for these GRE's and when I actually took them too. I'm not asking what my chances are, because obviously it's hard to guage anyone's chances (if you want to give me your opinion I won't mind reading it though, my top Schools are Northwestern, U Chicago, and U Illinois U-C) but how and where I should try to explain this poor academic year. I felt like I had a weak start in school but ended up coming on pretty strong after that and was pretty proud of the turn around I had made. Now it seems like they might think I just got lazy again. Also, I likely won't have any more grades after this semester before I apply to show that I still have the motivation since I'm applying in the Fall and plan to be the first application turned in to each school I'm applying to this year. Opinions? Similar experiences? Advice?