I messed up fall quarter and don't know if I should explain it on the application...

I’m currently a sophomore student at UC Riverside, and sent an application to UC Berkeley and UCLA, applying as a Sociology major for both, and I added Political Science to UCLA. Up until the end of fall quarter, I had a 3.73 GPA, a 3.66 in Political Science and a 4.0 in Sociology. I messed up badly in fall: I went out a bit too much, and my ego was huge because I thought the classes I took (entomology, world history, criminology, and an honors seminar) would be easy. I ended up Pass/No Passing (passed the class) entomology, got a B+ in history, an A+ in honors, and a C+ in criminology. My GPA for fall quarter was a 3.0 (approx), and my overall GPA is now a 3.62.
This obviously looks really bad, and I’m aware that it’s completely my fault. I don’t know if I should explain this on the application updates, and if I do, how I should explain it because I don’t want to sound like I’m making excuses. I’m also wondering if I should change my major, as I have slightly more going for me for political science (I took an upper division class in European Union politics and was the only freshman).
I don’t have much in terms of ECs (part of sexual assault education peer group, did an internship at the SFPUC before freshman year, volunteered about 150 hours at the San Francisco Public Library in high school, and helped international students with their English, among other small things), and my boyfriend says that my essays are pretty good (why I chose the major I did was thanks to a political science/sociology teacher I had in high school who helped me not repeat sophomore year, and the personal quality one is why I love Finland so much, and how learning about the country helped shaped my personal views, and I kind of tied that to why I want to study political science/sociology).

I don’t think it is worth explaining, mostly because any attempt would sound like an excuse.

Also, I don’t think you can change majors after submitting the app.

https://www.admissions.ucla.edu/prospect/adm_tr/Tr_Prof14_mjr.htm#PW This website has the stats for UCLA sociology. You aren’t too far off the average GPA, so your essay could help you there.

When transferring to UC’s from another UC, they look at your grades exactly how they look at community college students’ grades. Also, UC’s, especially UCLA and Cal, accept WAAAAAAY more cc transfers than UC transfers. Given that the average GPA for both schools is above a 3.7, I’d say you probably screwed yourself last semester. Hopefully you picked a backup school to apply to?

I wouldn’t say anything either. It is what it is.