I'll address the side stitch.

This can be caused by two things. One is eating too much too close to the start of your ride, but your bonk seems to more indicate that was probably not the case. It can be caused by eating something your body disagrees with too close to a ride too (bananas give me awful cramp.... though I like them off the bike)

It can also be caused by not warming up. Don't go all out right off the start. Take some time to warm your body up and be ready to ride harder. Start slow and ramp it up a little at a time. Cramps from warming up sufficiently can be absolutely excruciating .