serious problem! please help?

i’ve been having stool problems

i had constipation/diarrhea for about a month but now its just constipation

so constipation for two months

and there have been black dots in my poo the whole time

its normal size but its usually one big piece not a lot of medium size which is what i had before the problem

my diet is pretty normal: veggies, meats, milk you know what everyone eats.

between sometimes and rarely i have gas but its only for a short time

at first i thought it was worms or some growth or whatever buti don’t really have any of those symptoms

help me please!!

(everything else is normal)