If you drop it, don't change your major because of one class! If you really want to be a nurse, keep at it!
I know some of the instructors have tests that are insane! I discovered this in chemistry last year. I took one look at the first quiz in August and didn't take my nose out of my chem book until MAY! He was one of those that explains things fine, notes seem fairly straightforward..then....WHAMO..on the test he seems to think his students have their masters in chemistry! Luckily he was a very nice man, though, so it made it hard to hate him too much
What was said above is good advice...I used the internet a great deal, because I was able to find many web-sites that made complex subjects very easy to understand. I agree that it would also be a very good idea to talk to the instructor before dropping.
Is it possible that the horribly fast pace of summer session courses is also adding to the problem? Maybe if you take it in the fall, it will be more manageable. Good luck, whatever you decide!