My baby of 2 months is having sudden crying fits, he wants to breastfeed constantly and when he falls asleep and i lay him down he wakes up and starts crying again?

Learned behavior: It is likely this is just learned behavior. If an infant learns to settle into sleep while feeding they can startle if they do not remain in the same position later. Your goal should be to stop feeds at least 1/2 hr before sleep & let baby learn to self settle into sleep. They did so in the womb. Now the breast or a pacifier can create such a problem if used as a sleep aid. Good luck.