Please help me with my hair.??

well i have long hair in layers..i am doing something thats messing up my hair...i dont no is i use the right brush..i have very thick hair and it gots splitted ends..i cut my points a month ago..but when i brush it-it gets puffy..my hair is the type that dont get puffy but why is it happening is it burnt..i dont straigthen my hair much..i do not use any chimicals i just die my hair but back then all this happen even with natural hair color..i think it is cuz i use a brush for thin hair cuz my moms hair is very thin...ppl LOVE my hair but i feel offended cuz i have a friend that told me i have ugly hair..i wash it everyday cuz if i dont it gets greesy(ewww)..do u think i should cut it a bit..i dont really want to..or should i use a comb or a right brush..if i use a comb would it work