pictures help. Brown is more of a sign of microbial growth. is it mushy or smell different in that area? if so, it is budrot. also, can peel open a bud gently and look for white fuzz underneath or brown mush.
It's possible they were burned, i guess... usually you get pale spots on leaves or mal-formed stigmata.
really bad light burn doesn't heal, but what you describe doesn't sound like light burn. Investigate further.
if fungus, carefully cut and remove infected parts. cut more than necessary... throw out more than necessary. to be safe.