My doctor says that i get stomachaches because of starving myself, which isn't true! he advised me to eat before going to bed! is that even possible?

Stomach pains: I will have to partially disagree. If u are starving yourself then your body reminds you to feed it by "growling" which may be painful. If your stomach hurts in the morning because u haven't eaten in 6-8 hours then that's normal and eating before going to bed may not necessarily change that. Eat a meal higher in protein than carbos 1-2 hours before bed and your stomach may improve.