i wasn't talking pre-reqs (well, perhaps indirectly) but rather that the school probably has a cap on how many hours you can take in a term and during the summer it's likely half of a regular semester. at my school, you'd be talking 20 hours (25 if you take GChem and OChem labs as well). this is asinine in a regular semester, let alone a shortened one. (keep in mind, i'm saying this with knowledge of how my school works--but your's would have to be drastically different to change what i'm saying).
did you start the pre-med process early? by the end of my soph year i'd completed both bios, both GChems (w/ lab) and OChemI--and I was BEHIND many other soph. pre-meds. the best advice i can give is to take an extra year to complete these courses. you could still do summer stuff, but you're talking about catching up with 25 hrs of core sciences (ie. stuff you really need for the MCAT) in about 8 weeks. sorry, bud, but unless your school has some really funky system in place it ain't gonna happen, even if you're a super genius--there's just way, way too much material in those classes. talk to your acad advisor--they'll be able to give you a reasonable timeline.