I got a call on Thursday by a UCSD representative that i had just gotten accepted to marshall college, but when i logged into the portal it said my college is revelle and my major is undeclared (i’m a comp sci major btw, and my alternate was math). I’m wondering if i should just call the school and get this sorted out.
Yes, you should give admissions a call on Monday. Did you happen to know the name of the person whom called your on Thursday?
Sadly, no 
All you can do is wait until Monday and try to sort this out. Best of luck and keep posters updated.