With a 3.77 sGPA you do not need a post bacc. (Unless you’re only aiming at stats-loving med schools like Penn, WashU or Vandy.)
See AMCAS FACTS Table A-23.
Students with a 3.60-3.79 GPA and an average MCAT 510 have a 60% chance of an acceptance into an MD program. Higher MCAT scores yield higher probabilities of success. A 3.77 GPA and 99th percentile MCAT has 75% chance gaining a med school acceptance.
So stop panicking.
In fact trying to raise an already very good 3.77 sGPA via a post-bacc may lead some adcomm members to worry about perfectionism/neuroticism–something that adcomms definitely don’t want in a future med student.
Remember your GPA is only one piece of the larger picture. Once you pass the minimum screening GPA for a school (which is lower than people typically think it is), your everything else become as important as your GPA
P.S. How’s your biochem grade?
EDIT:
Late P.P.S. Consider dropping the second major and the minor. Neither of those things will improve your chance for a med school acceptance. (Seriously, adcomms don’t care what you major in and are not impressed by you having additional majors/minors.) Dropping one or both will lighten your academic load so you can give your full attention to your required major and pre-med classes.